Sleep improvers

Abstract

This invention provides a sleep improver containing black soybean seed coat extract as an active ingredient, a food, supplement, medicine, quasi-drug, feed or pet food containing the sleep improver, and a method for imparting the sleep-improving effect.

Description

Sleep improvers The present invention relates to a sleep-improving agent, a method for producing the sleep-improving agent, a method for using the sleep-improving agent, and the like. According to the 2019 National Health and Nutrition Survey, the proportion of people who report some level of anxiety or distress regarding their sleep quality has risen to 69.1%. In particular, a high percentage of people cite issues such as "feeling sleepy during the day" and "being bothered by waking up during the night." Furthermore, reports indicate that the average sleep duration of Japanese people is decreasing year by year (Non-Patent Document 1). Reports link insufficient sleep to decreased work performance (Non-Patent Document 2), and as of 2016, economic losses in Japan due to sleep-related problems were estimated at 15 trillion yen (Non-Patent Document 3). Sleep problems are a social issue that requires urgent action. Treatments for impaired sleep quality include medications using sleep-enhancing drugs such as benzodiazepines and antihistamines. While these existing medications can improve sleep, they may not be a sufficient solution due to side effects such as psychiatric symptoms and muscle relaxation. On the other hand, since sleep-improving foods and beverages containing active ingredients derived from food contain previously consumed ingredients, they have fewer side effects than pharmaceuticals. So far, reported ingredients in foods and beverages with sleep-improving effects include theanine (Patent Document 1), glycine (Patent Document 2), ornithine (Patent Document 3), gamma-aminobutyric acid (GABA; Patent Document 4), arginine (Patent Document 5), glutathione (Patent Document 6), bacterial fragments of microorganisms belonging to Bacillus subtilis, such as Bacillus natto (Patent Document 7), sake yeast (Patent Document 8), zinc and sugars or sugar alcohols (Patent Document 9), casein hydrolysates and minerals (Patent Document 10), sesaminoids (Patent Document 11), pumpkin seed extracts (Patent Document 12), ash plants or extracts thereof, Siberian larch extracts, dihydroquercetin, dihydrokaempferol, or naringenin (Patent Document 13). However, people are looking for a device that can achieve a better sleep improvement effect. [Prior Art Documents] [Patent Documents] Patent Document 1: International Publication No. 2001 / 074352 Patent Document 2: Japanese Patent Application Publication No. 2006-333872 Patent Document 3: Japanese Patent Application Publication No. 2006-342148 Patent Document 4: Japanese Patent Application Publication No. 2007-63236 Patent Document 5: Japanese Patent Application Publication No. 2007-230954 Patent Document 6: Japanese Patent Application Publication No. 2008-56628 Patent Document 7: Japanese Patent Application Publication No. 2008-1 Patent Document 8: Japanese Patent Application Publication No. 2015-214518 Patent Document 9: International Publication No. 2015 / 099102 Patent Document 10: Japanese Patent Application Publication No. 2009-13143 Patent Document 11: Japanese Patent Application Publication No. 2010-285427 Patent Document 12: Japanese Patent Application Publication No. 2012-206943 Patent Document 13: International Publication No. 2013 / 051727 [Non-Patent Document] Non-patent literature 1: Ministry of Health, Labour and Welfare, Health Bureau, Health Section, Nutrition Guidance Office, 2019 National Health and Nutrition Survey Report, Ministry of Health, Labour and Welfare Non-patent literature 2: Okajima, I., Komada, Y., Ito, W., & Inoue, Y. (2021). Sleep debt and social jetlag associated with sleepiness, mood, and work performance among workers in Japan. International Journal of Environmental Research and Public Health, 18 (6), 2908 Non-patent literature 3: Hafner, M., Stepanek, M., Taylor, J., Troxel, WM, & Van Stolk, C. (2017). Why sleep matters-the economic costs of insufficient sleep: a cross-country comparative analysis. Rand health quarterly, 6 (4) [Problems to be solved by the invention] The present invention aims to provide a novel composition having a sleep-improving effect. [Technical Means for Solving the Problem] The present inventors have conducted intensive research to solve the above-mentioned problems and surprisingly found that taking a black soybean seed coat extract can improve sleep quality. This has led to the completion of the present invention. The present invention provides, for example, the following aspects. [1] A sleep-improving agent for improving sleep quality, comprising a black soybean seed coat extract as an active ingredient. [2] The sleep-improving agent as described in [1], wherein the sleep quality is at least one selected from the group consisting of (a) to (d): (a) sleepiness, (b) falling asleep and maintaining sleep, (c) fatigue recovery, and (d) sleep time. [3] The sleep-improving agent as described in [1] or [2], wherein the black soybean seed coat extract is an acidic extract of black soybean seed coat. [4] The sleep-improving agent as described in any one of [1] to [3], in the form of a food or beverage, a supplement, or a pharmaceutical composition. [5] A food or beverage for improving sleep, comprising the sleep-improving agent as described in any one of [1] to [4]. [6] A supplement for improving sleep, comprising the sleep-improving agent as described in any one of [1] to [4]. [7] An oral pharmaceutical composition for improving sleep, comprising the sleep-improving agent as described in any one of [1] to [4]. [8] A method for imparting a sleep-improving effect to the above composition, comprising adding a black soybean seed coat extract to the composition. [9] A method for producing a sleep-improving agent, comprising using a black soybean seed coat extract as an active ingredient. [Effects of the Invention] According to the present invention, a sleep-improving agent for improving sleep quality is provided. Since the sleep-improving agent contains a food-derived black soybean seed coat extract as an active ingredient, it has excellent safety and, as shown in the examples described below, also excellent effectiveness. Thus, according to the present invention, a sleep-improving agent that can be safely ingested by animals, represented by humans, is provided. Furthermore, by mixing the sleep-improving agent of the present invention or the black soybean seed coat extract as an active ingredient with materials such as food and beverages, supplements, pharmaceuticals, quasi-drugs, feed, and pet food, it is possible to produce food and beverages, supplements, pharmaceuticals, quasi-drugs, feed, and pet food that have a sleep-improving effect. In addition, by adding the sleep-improving agent of the present invention to an oral composition such as food and beverages, feed, and pet food, the oral composition can be given a sleep-improving effect. [1] Sleep improver The sleep improver of the present invention (hereinafter referred to as the "improver of the present invention") is a composition for improving sleep, characterized in that it contains an extract of black soybean seed coat as an active ingredient. In this specification, black soybeans refer to the black seeds (fruits) of Glycine max (L.) Merrill, a short-day annual plant belonging to the genus Soybean in the Fabaceae family. Black soybean varieties include Nakano Kokuro, Tokachi Black, Shukuro, Tamado Kokuro, Tanba Black, Shinano Black, and Karaburu. However, in this invention, any variety of black soybean seeds can be used. The raw material can be black soybean seed coats, obtained by subjecting black soybeans to a separation machine, for example, to separation into seed coats and embryos (cotyledons and hypocotyls). The black soybean seed coats can be fresh or dried, and can be in their original form after separation, or they can be crushed, pulverized, or chopped (including crushed, pulverized, mealy, powdered, and chopped forms). As a method for extracting from black soybean seed coats, commonly used methods can be utilized. Although not limited, examples include: a method of immersing fresh or dried black soybean seed coats (in their original form, or in a coarse meal, powder, chopped, crushed, or pulverized form) in a water-soluble solvent; a method of extracting while stirring as needed; or a percolation method, etc. The temperature conditions used for extraction are not particularly limited and can be any of low temperature, room temperature, and heated conditions (including high temperature), but heated conditions (including high temperature) are preferred to improve extraction efficiency. More specifically, when using the aqueous lower alcohol extraction described below, the temperature is above 30°C, preferably in the range of 40°C to 60°C. Although not limited, by extracting under these temperature conditions for at least 60 minutes, preferably about 90 minutes to 120 minutes, the target black soybean seed coat component (extract) can be fully extracted. When the extraction is performed with an acidic aqueous solution, the temperature is 50° C. or higher, preferably 50 to 80° C., although there is no limitation. However, the extraction is performed under these temperature conditions for 10 minutes or more, preferably 20 to 120 minutes. There are no particular restrictions on the water-soluble solvent used for extraction, and examples thereof include water, lower alcohols, or mixtures thereof. Examples of lower alcohols include methanol, ethanol, propanol, isopropanol, butanol, and other lower alcohols having 1 to 4 carbon atoms. A preferred example of lower alcohols is ethanol. A preferred example of water-soluble solvents includes water or hydrous lower alcohols (especially hydrous ethanol), and more preferably, water in terms of ease of operation during extraction or purification. Furthermore, when using hydrous lower alcohols as solvents, the amount of lower alcohols contained therein is preferably 80% by volume or less. To improve the stability of the black soybean seed coat component (extract), the aqueous solvent used for extraction is preferably acidic. While not particularly limited, the pH of the aqueous solvent is preferably in the range of approximately pH 1-4, particularly preferably pH 1-2. To adjust the pH of the aqueous solvent to this range, an appropriate acidic substance such as an organic acid or an inorganic acid is typically used. Specific examples of acidic substances include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and boric acid; and organic acids such as methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 10-camphorsulfonic acid, fluorosulfonic acid (all sulfonic acids), formic acid, acetic acid, citric acid, and oxalic acid (all carboxylic acids). Preferred are acids having a sulfonic group, specifically sulfuric acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 10-camphorsulfonic acid, and fluorosulfonic acid. Among these, sulfuric acid is preferred. By heating at a temperature of 50 to 80°C in the presence of an acid having a sulfonic group, a polyphenol-containing extract having a high content of oligomeric proanthocyanidins and a low content of cyanidin 3-glucoside can be obtained. Furthermore, regarding the acid equivalent concentration in the water-soluble solvent, there is no particular limitation as long as the water-soluble solvent is within the aforementioned pH range, but it is preferably in the range of 0.01 to 0.5 N, more preferably in the range of 0.03 to 0.5 N. The resulting black soybean hull extract can also be used directly as the improving agent of the present invention, but if necessary, it can be further purified by filtration, coprecipitation, centrifugation, or other purification processes such as solid removal, activated carbon treatment, and adsorption treatment. For example, to increase the concentration of polyphenols in the black soybean hull extract, a synthetic adsorbent can be used for purification. Synthetic adsorbents include, for example, porous cross-linked polymer resins such as styrene and methacrylate. Styrene-based resins include, for example, Diaion HP20, HP21, Sepabeads SP825, SP70, and SP700. Acrylic resins include, for example, Diaion HP2MGL and Amberlite XAD7HP. Purification using synthetic adsorbents can be performed using previously known methods. For example, the resulting extract can be passed through a synthetic adsorbent filled in a glass tube for adsorption. After rinsing with water to remove impurities or acid, the polyphenols adsorbed on the resin can be dissolved using an organic solvent or a mixture of an organic solvent and water. The black soybean seed coat extract prepared in this way can also be used directly as the improving agent of the present invention, but from the perspective of taking or the perspective of food and beverage manufacturing, it can be subjected to concentration treatment and / or drying treatment. Furthermore, as needed, in order to reduce the number of bacteria in the extract or improve the preservation of the extract, a sterilization treatment can be implemented within the scope that does not damage the effect of the present invention. The sterilization treatment can be carried out, for example, by well-known methods such as UHT sterilization (Ultra-high temperature instantaneous sterilization) and steaming sterilization. Furthermore, the black soybean seed coat extract in the present invention can be any one of an extract, a diluted solution or concentrated solution of the extract, or a dried product obtained by drying the extract. The black soybean seed coat extract prepared as described above preferably contains polyphenols at a content of about 30% w / w or greater, more preferably about 40% w / w or greater, for example, about 50% w / w to 70% w / w, and even more preferably about 55% w / w to 65% w / w. More preferably, the black soybean seed coat extract contains proanthocyanidins and the monomers constituting proanthocyanidins, namely, catechin and epicatechin, in a total content of 10% w / w or greater, preferably 15% w / w or greater, more preferably 20% w / w or greater, even more preferably 25% w / w or greater, and even more preferably 30% w / w or greater of the polyphenols. More preferably, the absorbability into the body can be improved by containing oligomeric (dimer to nonamer) proanthocyanidins such as procyanidin B2, procyanidin C1, and cinnamtannin A2, or monomers constituting proanthocyanidins, namely catechin and epicatechin. The sleep-improving agent of the present invention has a sleep-improving effect. In this specification, "sleep improvement" refers to "improvement in sleep quality." Sleep quality primarily refers to the psychological sensations felt (or recognized or evaluated) upon waking. Improved sleep quality, for example, refers to improvements in the feeling of falling asleep quickly, feeling deeply asleep, feeling refreshed, feeling relaxed, being able to concentrate, being able to fall asleep, and recovering from fatigue. In this specification, "sleep quality" is evaluated, for example, based on the five factors of the OSA Sleep Inventory (MA version). The OSA Sleep Inventory (MA version) is a psychological scale developed and standardized by Shuichiro Shirakawa, Chairman of the Japan Sleep Improvement Association, to assess introspective sleep upon waking. The inventory consists of 16 items across five factors: Factor 1: Sleepiness on Rising, Factor 2: Initiation and Maintenance of Sleep, Factor 3: Frequent Dreaming, Factor 4: Refreshing, and Factor 5: Sleep Length. Each item is a four-choice questionnaire, with higher scores indicating better sleep. The OSA Sleep Inventory (MA version) has undergone comprehensive standardization procedures, resulting in high reliability and reproducibility. The sleep quality measured in this inventory is a statistical scale of daily fluctuations in sleep quality. The improving agent of the present invention is preferably capable of improving at least one sleep quality selected from the group consisting of the following (a) to (d): (a) sleepiness, (b) sleep onset and sleep maintenance, (c) fatigue recovery, and (d) sleep duration. [2] Oral Composition The improving agent of the present invention is preferably an oral composition in any form that can be taken (or administered) orally. By taking (administering, taking) the improving agent of the present invention orally, sleep quality can be improved. As long as the oral composition is in a form for oral ingestion (or administration), its use is not particularly limited, and examples thereof include pharmaceutical compositions, foods and drinks, and supplements. In this specification, pharmaceutical compositions include pharmaceuticals and quasi-drugs. In this specification, foods and drinks and supplements include health functional foods such as specific health foods with efficacy indications approved by prescribed authorities, functionally labeled foods, and nutritional functional foods. Examples of such so-called health foods include those with claims of "improving sleep quality," "improving the feeling of deep sleep," "reducing the number of awakenings during sleep," "improving sleep depth," "improving sleep rhythm," "increasing satisfaction upon waking up," "improving the feeling of prolonged sleep time," "supporting quality sleep at night," and "improving the ability to fall asleep," etc. The oral composition is preferably a food or beverage or supplement, more preferably a food or beverage or supplement that is a specific health food or functional food with a claimed effect or efficacy. Furthermore, the oral composition may be a feed or pet food intended for animals other than humans (including livestock, poultry, and pets). Examples of the oral ingestion (or administration) form include liquid, jelly, and solid forms. The improving agent of the present invention can be in the form of a pharmaceutical composition or supplement. Specifically, the following dosage forms can be exemplified: a black soybean seed coat extract prepared by the above-mentioned extraction method is prepared into a liquid (including an extract or syrup) or gel; a powder, fine granules, or granules prepared by conventional methods from the extract; a capsule (hard capsule, soft capsule) formed by filling the liquid, powder, or granules into a capsule; or a tablet formed by pressing the powder or granules into a tablet. The improving agent of the present invention can be the black soybean seed coat extract itself, or it can be prepared in various oral ingestion (or administration) forms by combining the black soybean seed coat extract with pharmaceutically acceptable edible carriers or additives acceptable in the food, beverage, or feed industries. Additives such as excipients, disintegrants, binders, surfactants, absorption enhancers, adsorbents, fillers, preservatives, stabilizers, emulsifiers, and solubilizers can be appropriately selected depending on the dosage form of the improving agent of the present invention. Carriers and additives known in the art can be used. For example, when the improving agent of the present invention is prepared in the form of a liquid, water, ethanol, sucrose, invert sugar, glucose, maltose, reduced syrup, etc. can be used as the above-mentioned carrier or additive. For example, when the improving agent of the present invention is made into a solid dosage form such as a tablet, the following excipients can be used: lactose, sugar, sodium chloride, glucose, urea, starch, calcium carbonate, kaolin, silicic acid, etc.; water, ethanol, propanol, simple syrup, glucose solution, starch solution, gelatin solution, carboxymethyl cellulose, shellac, methyl cellulose, potassium phosphate, polyvinyl pyrrolidone, crystalline cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, sodium alginate, etc.; dry starch, agar powder, kelp, etc. Disintegrants include: powder, sodium bicarbonate, polyoxyethylene sorbitan fatty acid esters, sodium lauryl sulfate, monoglyceride of stearic acid, starch, cross-linked polyvinylpyrrolidone, povidone, and low-substituted hydroxypropyl cellulose; disintegration inhibitors such as stearin, cocoa butter, and hydrogenated oil; absorption enhancers such as quaternary ammonium salts and sodium lauryl sulfate; humectants such as glycerin; adsorbents such as starch, lactose, kaolin, bentonite, and colloidal silicic acid; and lubricants such as purified talc, stearates, boric acid powder, and polyethylene glycol. Furthermore, tablets can be prepared as needed with conventional coatings, such as sugar-coated tablets, gelatin-coated tablets, enteric-coated tablets, film-coated tablets, or double-coated or multiple-coated tablets. Alternatively, the composition containing the active ingredient can be filled into conventional capsules made from gelatin, pullulan, starch, gum arabic, hydroxypropyl methylcellulose (HPMC), and the like to prepare capsules. When the preparation is in the form of pills, for example, excipients such as glucose, lactose, starch, cocoa butter, hydrogenated vegetable oil, kaolin, talc, binders such as gum arabic powder, tragacanth powder, gelatin, ethanol, and disintegrants such as laminarin and agar can be used. These dosage forms can be prepared using conventional methods in the art. For example, tablets can be prepared by adding the aforementioned active ingredients and other excipients necessary for tablets, thoroughly mixing and dispersing them, and then forming them into tablets. For example, powders can be prepared by adding the aforementioned active ingredients and other excipients necessary for powders, mixing them, and then pulverizing them using a preferred method. In addition to the above-mentioned dosage forms, the improving agent of the present invention may also be in the form of food and beverages. Food and beverages are not particularly limited as long as they are in any form that can be taken orally, such as solution, suspension, emulsion, jelly (gel), sol, powder, solid formed product, etc. Specifically, for example, instant foods such as instant noodles, steamed foods, canned foods, microwave foods, instant soups / miso soups, and cold-dried foods; beverages such as soft drinks, fruit juice drinks, vegetable drinks, soy milk drinks, coffee drinks, tea drinks, powdered drinks, concentrated drinks, nutritional drinks, and alcoholic drinks; wheat flour products such as bread, pasta, noodles, cake mix powder, dry fried food powder, and bread flour; pastries such as malt sugar, caramel, chewing gum, chocolate, cookies, biscuits, cakes, pies, snacks, crackers, Japanese-style snacks, and desserts; sauces, Condiments such as processed tomato seasonings, flavored seasonings, seasoning mixes, sauces, salad dressings, soups, and curry / stew ingredients; processed fats and oils such as butter, margarine, and mayonnaise; dairy products such as milk beverages, yogurts, cheese, fermented milk, lactic acid bacteria beverages, ice cream, and fresh cream; egg-processed products such as pudding and mayonnaise; processed seafood such as fish ham and refined seafood products; processed livestock products such as livestock ham; processed agricultural products such as canned agricultural products, marmalades, pickles, boiled beans, and cereals; frozen foods and nutritional foods. While not limiting, polyphenols derived from black soybean seed coat extract are more stable in acidic conditions. Therefore, acidic foods are preferred to suppress precipitation and color tone reduction. Such foods and drinks can be produced, for example, by mixing the black soybean seed coat extract with the ingredients of the food and drink during the production process. Furthermore, the improving agent of the present invention may be in the form of feed or pet food. Examples of the feed or pet food include pills, pastes, granules, crumbs, flakes, and puffed products. The feed or pet food can be produced by, for example, appropriately mixing the black soybean hull extract with feed or pet food ingredients and the aforementioned carriers or additives during the production process. Furthermore, the improving agent of the present invention can be an additive added to pharmaceutical compositions, food and beverages, supplements, feeds, or pet foods. The additive can be added to the manufactured composition, or can be added or mixed into the raw materials during the manufacturing process. The composition is preferably an oral composition. The upper limit of the content of black soybean seed coat extract in the improving agent of the present invention is set at 100% by mass and can be appropriately set depending on the type of dosage form or the type of application (e.g., pharmaceutical composition, food and beverage, supplement, feed, pet food, additive, etc.). The intake (dosage) of the composition of the present invention can be appropriately varied depending on the type of subject (human or various animals), gender or age, and the subject's condition or severity of symptoms. Although not limiting, for example, the daily intake (dosage) for an adult (weighing 50 kg) is generally about 10 to 500 mg of black soybean seed coat extract (dry weight) contained in the improving agent of the present invention, for example, about 25 to 400 mg, preferably about 50 to 300 mg. It is generally used in the form of oral administration (ingestion) once a day or divided into 2 to 3 doses. The time of ingestion (administration) is not particularly limited and can be, for example, in the morning, at noon, or in the evening with a meal. Also, although there is no restriction, it can be taken with meals or within 30 minutes before or after meals. [3] Method of using black soybean seed coat extract The present invention also provides a method of using black soybean seed coat extract (hereinafter, also referred to as "method of using the present invention"). One aspect of the method of using is a method of using black soybean seed coat extract for imparting a sleep-improving effect to a composition, comprising blending the black soybean seed coat extract into the composition. Another aspect is a method of using black soybean seed coat extract for preparing a composition for improving sleep. In this specification, blending includes adding and mixing. The above-mentioned method of using includes, for example: adding the black soybean seed coat extract to the manufactured composition; or adding or mixing the black soybean seed coat extract to the raw materials of the composition during the manufacturing process of the composition. The above-mentioned composition is a pharmaceutical composition, a food and beverage, a supplement, a feed, a pet food, etc., preferably an oral composition. Oral compositions include compositions for orally administering to humans or animals, or compositions ingested by humans or animals, and specifically include oral pharmaceuticals, oral quasi-drugs, foods and drinks, supplements, feeds, pet foods, and the like. The amount of black soybean seed coat extract added to or formulated in the oral composition is not particularly limited, as long as it imparts a sleep-improving effect to the oral composition. As another aspect of the method of use of the present invention, a method for improving sleep comprising administering a black soybean seed coat extract to a subject is provided. Examples of subjects include humans and animals other than humans (e.g., livestock, poultry, pets, etc.). The dosage of the black soybean seed coat extract can be appropriately determined based on the type, gender, or age of the subject, the subject's condition, or the severity of the symptoms. Although not limited, for example, the daily dosage for an adult (50 kg in weight) is generally about 10 to 500 mg, for example, about 25 to 400 mg, preferably about 50 to 300 mg. It is usually administered orally once a day or divided into 2 to 3 doses. In the method of use of the present invention, the improving agent of the present invention containing the black soybean seed coat extract as an active ingredient may also be used instead of the black soybean seed coat extract. Furthermore, as another aspect of the present invention's method of use, a method for producing the sleep-improving agent of the present invention, comprising using a black soybean seed coat extract as an active ingredient, is provided. This method, for example, comprises mixing the black soybean seed coat extract with a carrier and / or additive suitable for the desired dosage form or shape. The desired dosage form or shape can then be formed using conventional methods. The carrier and additive are as described above. The types of black soybeans used as raw materials for the black soybean seed coat extract, the method for obtaining the black soybean seed coat, the black soybean seed coat extract, and especially the method for preparing the black soybean seed coat acidic extract as a preferred embodiment of the extract are as described in [1] above and can be used in this section. [Examples] Hereinafter, the present invention will be described in more detail with reference to experimental examples, but the present invention is not limited thereto. Example 1: Improvement of Sleep Quality by Black Soybean Coat Extract First, the preparation methods of black soybean coat extract and test food are described, followed by the test methods and results related to sleep improvement. [Black soybean seed coat extract] Black soybean seed coat extract (acidic hot water extract) is prepared by the following method. (1) 1 kg of fresh black soybean seed coat is immersed in 30 L of dilute sulfuric acid (0.3% w / v) as an extraction solvent, and the mixture is stirred and extracted for 20 minutes while being heated to 55-60°C. (2) After extraction, the black soybean seed coat and the liquid are separated by solid-liquid separation, and the liquid is recovered. (3) The recovered liquid is centrifuged to remove suspended solids that could not be removed during the solid-liquid separation. (4) The obtained extract is added to a column filled with a synthetic adsorption resin (Sepabeads SP700: manufactured by Mitsubishi Chemical) and adsorbed on the resin. (5) In order to flush out the sulfuric acid remaining in the column, water is passed through the column to clean the resin. (6) A 59% by volume alcohol aqueous solution is passed through the column to elute the polyphenols adsorbed on the resin. (7) The recovered eluate (alcohol solution) was evaporated and concentrated by heating under reduced pressure. (8) Dextrin was added as an excipient to the obtained concentrated solution. (9) Heat sterilization was performed. (10) The heat-sterilized concentrated solution was spray-dried to obtain a black soybean seed coat extract (85 g, polyphenol content of extract 1: 61.10%, extract 2: 58.08%). [Composition of Black Soybean Seed Coat Extract] The composition of the black soybean seed coat extract (acidic hot water extract) obtained above was analyzed by the following method. (1) Total Polyphenol Analysis: A sample solution was prepared by adjusting the black soybean seed coat extract to a concentration of 7.5 mg / 100 ml using 70% ethanol. 5 ml of the Flintol solution was added to 1 ml of the sample solution to allow for reaction. 4 ml of a 0.7 M sodium carbonate aqueous solution was added and stirred. After standing at 30°C for 60 minutes, the absorbance at 765 nm was measured using a spectrophotometer. A calibration curve was also prepared for catechin (manufactured by SIGMA, "(+)-catechin hydrate" C1251-5G), and the total polyphenol content was calculated as the catechin equivalent. (2) Total Flavan-3-ol Analysis: A sample solution was prepared by adjusting the black soybean seed coat extract to a concentration of 12.5 mg / 100 ml with 50% ethanol. 3 ml of a 4% vanillin solution was added to 1 ml of the sample solution and stirred. 1.5 ml of concentrated hydrochloric acid was added and stirred. The solution was allowed to stand at 30°C for 20 minutes, and the absorbance at 500 nm was measured using a spectrophotometer. Furthermore, 100% methanol was added to the control area instead of the 4% vanillin solution. The spectrophotometer was used to determine the absorbance of the test area, the control area, and the blank area, respectively, using the formula: absorbance of the specimen = A - B - C. A calibration curve for catechin (manufactured by SIGMA, "(+)-catechin hydrate" C1251-5G) was also prepared, and the total flavan-3-ol content was calculated as the catechin equivalent. (3) Analysis of Catechin, Epicatechin, Procyanidin B2, Procyanidin C1, and Cinnamtannin A2: Black soybean seed coat extract was adjusted to a concentration of 0.1 mg / ml with 50% ethanol to prepare a sample solution. The sample solution was then analyzed by HPLC (high performance liquid chromatography) under the following analytical conditions. The analytical conditions were 0.1% formic acid solution as mobile phase A and acetonitrile as mobile phase B, with elution using the following concentration gradient and conditions. Furthermore, standard solutions of catechin, epicatechin, procyanidin B2, procyanidin C1, and cinnamtannin A2 were simultaneously tested on HPLC to create a calibration curve for quantification. Concentration gradient: 0-45 min / B: 5-15%, 45-50 min / B: 15-80%, 50-53 min / B: 80%, 53-70 min / B: 5%, flow rate: 0.7 mL / min, injection volume: 10 μL, column oven temperature: 40°C, fluorescence: excitation wavelength 276 nm, luminescence: 316 nm, Cadenza CL-C18 column ( φ250 mm×4.6 mm, 3 μm, Imtakt), guard column (Cadenza CL-C18, φ5 mm×2 mm, 3 μm, Imtakt) (4) Cyanidin 3-glucoside Analysis: Black soybean seed coat extract was adjusted to a concentration of 0.1 mg / ml using 1% hydrochloric acid-methanol (1:37, v / v) to prepare a sample solution. The sample solution was then analyzed by HPLC under the following analytical conditions. The analysis conditions were formic acid:water (3:97, v / v) as mobile phase A and formic acid:acetonitrile:water (3:30:67, v / v) as mobile phase B. The elution was performed under the following concentration gradient and conditions. A standard solution of cyanidin 3-glucoside was also tested on the HPLC to create a calibration curve for quantification. Concentration gradient: 0-50 min / B: 25-50%, 50-55 min / B: 50-100%, 55-60 min / B: 100%, 60-70 min / B: 25%, flow rate: 0.6 mL / min, injection volume: 10 μL, column oven temperature: 40°C, UV: measurement wavelength 520 nm, Cadenza CL-C18 column ( φ250 mm×4.6 mm, 3 μm, Imtakt), guard column (Cadenza CL-C18, ϕ5 mm×2 mm, 3 μm, Imtakt) The black soybean seed coat extraction test was conducted twice using different batches of black soybean seed coat raw materials. The analysis results of the component compositions of the extracts obtained each time (Extract 1 and Extract 2) are shown in Table 1. [Table 1] [Test Foods] The test foods used were foods containing black soybean seed coat extract (Test Foods 1 and 2) and a control food (placebo). The formulations of each test food are as follows: (Test Food 1: Low Dose 100 mg / day) Three tablets containing 100 mg of black soybean seed coat extract (polyphenol content 58%) (Test Food 2: High Dose 300 mg / day) Three tablets containing 300 mg of black soybean seed coat extract (polyphenol content 58%) (placebo) Tablets without black soybean seed coat extract (replaced with dextrin). Furthermore, the placebo was formulated to have no significant differences in calories and other aspects from the test foods. Table 2 shows the nutritional composition of each test food. [Table 2] [Test Method] This double-blind, parallel-group comparative study involved 69 subjects (aged 20-65, average age 41) divided into three groups (placebo group, 21 participants), low-dose group, and high-dose group (23 participants). The subjects consumed three tablets of each test food (low-dose or high-dose test food, or placebo) for 12 weeks, and capillary blood flow measurements and sleep quality assessments were performed. The OSA Sleep Questionnaire (MA version) was administered upon waking on weekdays to assess sleep quality, and capillary blood flow measurements were performed around 9:00 AM. Capillary measurements were performed before ingestion of the test food (any day within 2 weeks of ingestion) and 12 weeks after ingestion. Capillaries within the ring fingernail bed of the left hand were imaged using a capillary angioscope (AT Co., Ltd.). The number and length of capillaries were calculated using software (Capillary Analysis System, which digitizes and quantifies the images of capillaries). Sleep Quality Evaluation: Sleep quality was evaluated before (one week before) and 12 weeks after the test food intake. The OSA Sleep Questionnaire (MA) was administered upon waking up on five workdays. The average of the five workday data was used to assess sleep quality before and after 12 weeks of intake across five factors (Factor I: Sleepiness upon waking up; Factor II: Falling asleep and maintaining sleep; Factor III: Dreaming; Factor IV: Fatigue recovery; Factor V: Sleep duration). The OSA Sleep Questionnaire (MA) consists of the following 16 items, each evaluated in four stages. These 16 items are correlated with any of the five factors listed above (Factor I: Items 2, 4, 8, 14; Factor II: Items 3, 7, 10, 13, 16; Factor III: Items 9, 12; Factor IV: Items 1, 5, 11; Factor V: Items 6, 15). 1. Still feeling tired 2. Able to concentrate 3. Sleep soundly 4. Feeling liberated 5. Feeling lazy 6. Having an appetite 7. Frequent drowsiness before falling asleep 8. Clear-headed 9. Frequent nightmares 10. Sleeping well 11. Feeling unhappy 12. Frequent dreaming 13. Often waking up during sleep 14. Answering surveys quickly and immediately 15. Sleeping for a long time 16. Light sleep [Results and Discussion] <Improvement effect on capillaries> Compared with the placebo intake group, improvement of capillaries was confirmed in the test food intake group. Figure 1 shows the capillary microscopy images of the low-dose intake group before and 12 weeks after intake. Figures 2-1 and 2-2 show the changes in the number and length of capillaries in a graph. In both the low-dose and high-dose intake groups, an improvement effect was observed in the length of capillaries (there was a significant difference between the groups) (Figure 2-2). In particular, after 12 weeks of intake, the high-dose 300 mg intake group showed significant improvement in the length and number of capillaries compared with the placebo intake group (p < 0.05) (Figures 2-1 and 2-2). This shows that the number and length of capillaries can be improved by taking black soybean seed coat extract. Since the improvement of capillaries increases the amount of blood circulating to the extremities, it is believed that heat dissipation becomes active during sleep, lowering deep body temperature, thereby promoting sleep and improving sleep quality. <Improvement in Sleep Quality> Analyses were conducted on 65 participants who were eligible for evaluation before and 12 weeks after ingestion of the test food (4 participants were unable to be evaluated because they forgot to complete the OSA Sleep Questionnaire MA version). The results are shown in Figures 3 to 6. While no significant differences were observed between groups, improvements were observed in sleep quality measures other than Factor III (dreaming) with the black soybean seed coat extract. Within-group comparisons showed improvements over time in Factor I (drowsiness upon waking), Factor IV (fatigue recovery), and Factor V (sleep duration) in the black soybean seed coat extract group. The following are examples of black soybean seed coat extract formulations. Formulation Example 1: Soft Capsules: Soft capsules were prepared using the following raw materials according to conventional procedures. Furthermore, the black soybean seed coat extract prepared according to the method of Experimental Example 1 was used as the black soybean seed coat extract. Vegetable oil: 158.6 mg, Gelatin: 135.2 mg, Black soybean seed coat extract: 100 mg, Glycerin: 30.2 mg, Lecithin: 30 mg, Beeswax: 26 mg, Vitamin E: 20 mg. Formulation Example 2: Tablets: Tablets were prepared using the following raw materials according to conventional methods. In addition, the black soybean hull extract prepared according to the method of Example 1 was used as the black soybean hull extract. Dextrin: 179.69 mg, Black soybean hull extract: 100 mg, Reduced syrup: 28.56 mg, Crystalline cellulose: 26.51 mg, Calcium stearate: 5.25 mg, Micro-particle silicon dioxide: 5.25 mg, Hydroxypropyl cellulose: 4.77 mg. Recipe Example 3: Individually Packaged Stick Jelly: Individually packaged stick jelly is prepared conventionally using the following ingredients. Furthermore, the black soybean seed coat extract prepared according to the method of Example 1 is used as the black soybean seed coat extract. Low-sugar syrup: 1000 mg, black soybean seed coat extract: 100 mg, gelling agent (thickening polysaccharide): 100 mg, sweetener (xylitol, sucralose, thaumatin, acesulfame potassium): 70 mg, flavoring: 20 mg, water: 8710 mg [Industrial Applicability] The sleep-improving agent containing the black soybean seed coat extract as an active ingredient of the present invention is useful because it can be used in a wide range of applications, including pharmaceuticals, quasi-drugs, food and beverages, supplements, feed, and pet food. Figure 1 is a capillary microscopic image of a subject after taking black soybean seed coat extract. Figure 2-1 shows the improvement effect of the number of capillaries of the subject after taking black soybean seed coat extract. Figure 2-2 shows the improvement effect of the length of the capillaries of the subject after taking black soybean seed coat extract. Figure 3 shows the evaluation results of the sleep quality (Factor I) of the subject after taking black soybean seed coat extract. Figure 4 shows the evaluation results of the sleep quality (Factor II) of the subject after taking black soybean seed coat extract. Figure 5 shows the evaluation results of the sleep quality (Factor IV) of the subject after taking black soybean seed coat extract. Figure 6 shows the evaluation results of the sleep quality (Factor V) of the subject after taking black soybean seed coat extract.

Claims

1. A sleep improver for improving sleep quality, comprising black soybean seed coat extract extracted at 50-80°C in the presence of an sulfonic acid as an active ingredient.

2. The sleep improver as requested in item 1, wherein the aforementioned sleep quality is selected from at least one of the following groups (a) to (d): (a) sleepiness upon waking, (b) sleep onset and sleep maintenance, (c) fatigue recovery, and (d) sleep duration.

3. The sleep improver as requested in item 1 or 2 is in the form of a food product, supplement, or pharmaceutical composition.

4. A method for imparting a sleep-improving effect to a composition, comprising blending a black soybean seed coat extract extracted at 50-80°C in the presence of an acid having an sulfonic acid into the above composition.

5. A method for manufacturing a sleep improver, comprising using black soybean seed coat extract extracted at 50-80°C in the presence of an acid containing sulfonyl groups as an active ingredient.

6. The method of claim 4, wherein the above-mentioned sleep-improving effect is an improvement of at least one of the effects selected from the group consisting of (a) to (d) below: (a) sleepiness upon waking, (b) falling asleep and maintaining sleep, (c) fatigue recovery, and (d) sleep duration.

7. The method of claim 5, wherein the aforementioned sleep improver has an effect of improving at least one of the following selected from (a) to (d): (a) drowsiness upon waking, (b) sleep onset and sleep maintenance, (c) fatigue recovery, and (d) sleep duration.

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