Composition for improving quality of sleep

Abstract

The purpose of the present invention is to provide a new means that is for improving the quality of sleep and that can be used on a daily basis. The present invention pertains to a composition that is for improving the quality of sleep, and that contains yeast mannan.

Description

Composition for improving sleep quality

[0001] The present invention relates to a composition for improving sleep quality, and in particular to a composition for improving sleep quality that can be used daily.

[0002] Sleep plays a major role in the recovery of the brain and body and is considered important for living a healthy life. However, in modern society, an increasing number of people suffer from sleep disorders and a decline in their quality of life (QOL) due to irregular lifestyles and a nocturnal lifestyle. Many people also suffer from a decline in QOL due to sleep disorders associated with aging. Therefore, there is a demand for materials that improve sleep quality and enhance QOL. For example, Patent Document 1 describes a sleep quality improver containing Lactobacillus casei cells and / or a processed product thereof as an active ingredient. However, a sleep quality improver with sufficient improvement effects has not yet been developed.

[0003] On the other hand, mannan purified from yeast cell walls is known as "yeast mannan," and research into its application is being conducted as a functional material with various effects. For example, Patent Document 2 describes an agent containing yeast mannan that reduces the intestinal Fb ratio ([occupancy rate of bacteria belonging to the phylum Firmicutes / occupancy rate of bacteria belonging to the phylum Bacteroidetes]), Patent Document 3 describes a mucin production promoter and a fucosylation promoter containing yeast mannan, and Patent Document 4 describes an equol production promoter, a premenstrual syndrome improver, and a skin condition improver containing yeast mannan. However, none of these documents describe the effect of yeast mannan on sleep.

[0004] International Publication No. WO 2015 / 146844 International Publication No. WO 2019 / 142844 International Publication No. WO 2019 / 142846 International Publication No. WO 2020 / 004568

[0005] The present invention aims to provide a new means for improving sleep quality that can be used daily.

[0006] As a result of intensive research aimed at solving the above-mentioned problems, the present inventors have found that ingestion of yeast mannan improves sleep quality, and have thus completed the present invention. Specifically, the present invention provides the following compositions and the like: [1] A composition for improving sleep quality, comprising yeast mannan. [2] The composition described in [1] above, for improving at least one selected from the group consisting of sleep depth, falling asleep, sleepiness, sleep time, sleep efficiency, and awakening during sleep. [3] The composition described in [1] or [2] above, in which the yeast mannan content is 0.05% by mass or more and 90% by mass or less, in terms of α-mannan, relative to the total mass of the composition. [4] The composition described in any one of [1] to [3] above, in which the daily intake amount of the yeast mannan is 0.1 g or more and 10.0 g or less, in terms of α-mannan. [5] The composition described in any one of [1] to [4] above, in the form of a food or drink. [6] A method for improving sleep quality, comprising a step of administering the composition according to any one of [1] to [5] to a subject. [7] Use of yeast mannan for producing the composition according to any one of [1] to [5]. [8] An agent for improving sleep quality, comprising yeast mannan. [9] Non-therapeutic use of yeast mannan as an agent for improving sleep quality.

[0007] According to the present invention, the quality of sleep can be improved by ingesting yeast mannan. Since yeast mannan is also used as a food ingredient and can be ingested on a daily basis, it is possible to improve the quality of normal sleep and thereby enhance QOL.

[0008] 1 shows the effect of yeast mannan on PSQI total score (mean ± standard error), 2 shows the effect of yeast mannan on the change in PSQI total score (mean ± standard error), and 3 shows the effect of yeast mannan on daytime wakefulness score (mean ± standard error).

[0009] The present invention is described in more detail below. The present invention relates to a composition for improving sleep quality. Sleep disorders occur when sleep quality declines due to aging, stress, or daily lifestyle habits. Insomnia, a type of sleep disorder, is diagnosed when a patient complains of insomnia symptoms and one or more daytime functional disorders are also present. Insomnia symptoms include difficulty falling asleep, waking up during the night, waking up early in the morning, and not feeling like one has slept well. Daytime functional disorders include fatigue, discomfort, decreased attention, concentration, and memory, daytime sleepiness, impaired social or occupational functioning, impaired academic performance, mood disorders, irritability, decreased motivation, activity, or initiative, making mistakes at work, increasing the likelihood of driving accidents, tension due to lack of sleep, headaches or gastrointestinal symptoms, and worries or concerns about sleep.

[0010] According to the American Academy of Sleep Medicine, sleep is divided into three stages: wakefulness (W), rapid eye movement (R), and non-REM sleep, in order of lightest to lightest sleep. Non-REM sleep is further divided into three stages, N1 to N3, depending on the depth of sleep. The deepest stage, N3, is also known as "deep sleep" or "slow-wave sleep." It is believed to be associated with a sense of deep sleep (depth of sleep) and is important for mental and physical health. It is also known that growth hormone secretion increases during N3. Growth hormone is an important hormone for cell and skin repair, stress relief, anti-aging, and physical growth in children. Growth hormone secretion is closely related to deep sleep, which occurs during the first sleep cycle, and is secreted in large amounts during the three hours of deep sleep after falling asleep. Meanwhile, the time from sleep onset to the first REM sleep is also known as the "REM sleep latency." It is known that REM sleep latency shortens with aging, stress, and a nocturnal lifestyle (e.g., staying up late at night). A shortened REM sleep latency means a shortening of the time of the first non-REM sleep mentioned above (the sum of N1 to N3), and since the repair of brain nerve cells that is supposed to take place during this time is not carried out sufficiently, it can be said that this sleep structure makes it difficult for sleep to function as it should.

[0011] The term "sleep quality" as used herein refers to a sleep state that comprehensively considers, for example, sleep depth, falling asleep, sleepiness, sleep time, sleep efficiency, sleep rhythm, fatigue, stress, dreaminess, and / or awakening during sleep. In one embodiment, the composition for improving sleep quality of the present invention may be intended to improve at least one selected from the group consisting of sleep depth, falling asleep, sleepiness, sleep time, sleep efficiency, and awakening during sleep. The method for evaluating sleep quality can be any method commonly used in the art, without particular limitation. However, for example, sleep quality may be evaluated by objective methods such as electroencephalography and / or subjective methods such as the Pittsburgh Sleep Quality Index (PSQI) or the Oguri-Shirakawa-Azumi Sleep Inventory (MA Version).

[0012] Specific examples of means for evaluating sleep quality are listed below, but are not limited to these. Sleep depth may be evaluated by measuring various parameters such as deep sleep time, deep sleep occurrence rate, REM sleep latency, or delta power during non-REM sleep. Falling asleep may be evaluated by measuring deep sleep latency, sleep onset latency, or sleep latency, or by investigating factor 2 of the OSA Sleep Questionnaire MA version or the sleep onset score of the PSQI. Sleepiness may be evaluated by investigating factor 1 of the OSA Sleep Questionnaire MA version or the daytime sleepiness score of the PSQI. Sleep duration may be evaluated by measuring total time in bed (TIB), total sleep time (TST), or sleep period time (SPT), or by investigating factor 5 of the OSA Sleep Questionnaire MA version or the sleep duration score of the PSQI. Sleep efficiency may be evaluated, for example, by calculating TST / TIB or TST / SPT, or by investigating the PSQI sleep efficiency score. Sleep rhythm may be evaluated, for example, by measuring sleep cycles. Fatigue may be evaluated, for example, by investigating the fourth factor of the OSA Sleep Questionnaire MA version, the Occupational Stress Questionnaire, or the Visual Analogue Scale (VAS) for fatigue. Dreaminess may be evaluated, for example, by investigating the third factor of the OSA Sleep Questionnaire MA version. Sleep awakenings include, for example, mid-sleep awakenings and early morning awakenings. Mid-sleep awakenings may be evaluated, for example, by measuring mid-sleep awakenings and awakening responses during sleep time (SPT), specifically, the awakening index (total number of awakenings per hour, number of epochs), awakening reaction time / epoch (awakening reaction time per epoch), the sum of continuous awakening times (total time during which awakenings last 3 minutes (6 epochs) or more), or the total awakening time.Early morning awakening may be evaluated, for example, by measuring the awakening and awakening response in the two hours before waking up, specifically the awakening index (total number of awakenings per hour, number of epochs), awakening reaction time / epoch (awakening reaction time per epoch), total continuous awakening time (total time during which awakening lasted for 3 minutes (6 epochs) or more), or total awakening time.

[0013] The composition of the present invention contains yeast mannan as an active ingredient. As used herein, "yeast mannan" refers to a substance containing at least one of yeast-derived "α-mannan" and yeast-derived "α-mannan-protein complex." Both α-mannan and α-mannan-protein complex are major components that constitute the cell wall of yeast.

[0014] The above-mentioned "α-mannan" is a polysaccharide in which D-mannose is polymerized via α1,6-bonds, α1,2-bonds, or α1,3-bonds, and one or more mannopyranoses may be bonded as side chains via α1,2-bonds or α1,3-bonds to the main chain composed of α1,6-bonds.

[0015] The above-mentioned "α-mannan-protein complex" is a water-soluble glycoprotein in which one or more α-mannan chains are bound to a protein localized in the cell wall of yeast via an N-glycosidic or O-glycosidic bond. The "α-mannan chain" bound by this glycoprotein, like the above-mentioned "α-mannan," is a polysaccharide chain in which D-mannose is polymerized via an α1,6-bond, an α1,2-bond, or an α1,3-bond, and the main chain formed by the α1,6-bond may have one or more mannopyranoses bound as side chains via an α1,2-bond or an α1,3-bond. The protein in the "α-mannan-protein complex" is also considered to include a peptide of two or more amino acid residues. In other words, the "α-mannan-protein complex" may also include an "α-mannan-peptide complex."

[0016] The yeast mannan may be recovered in any manner as long as it is derived from yeast. For example, it may be yeast mannan obtained by damaging the yeast cell wall with an enzymatic or chemical treatment, and then separating and recovering (extracting), or it may be yeast mannan obtained by recovering the mannan released from the yeast into a medium. The yeast mannan may also be readily available as a commercially available product. Specific examples include "Mannan from Saccharomyces cerevisiae M7504" (Sigma-Aldrich Japan LLC).

[0017] The yeast cell walls may be prepared by any method commonly used in the art without any particular limitations, but may also be obtained as the residue from which a yeast extract is extracted from yeast used in the production of beer, sake, bread, etc. Alternatively, the yeast cell walls may be obtained from products such as those sold by Asahi Group Foods Co., Ltd. under the trade name "Yeast Cell Wall" or other similar products.

[0018] The method for preparing yeast mannan from yeast cell walls may be any method commonly used in the art, without particular limitation, but may also include, for example, a step of obtaining a crude yeast mannan extract from yeast cell walls (hereinafter referred to as the "crude extraction step"), followed, if necessary, by a method including a step of purifying the crude yeast mannan extract to obtain purified yeast mannan (hereinafter referred to as the "purification step"). Optionally, a step of preparing the cell walls from yeast may be included before the crude extraction step, but such a step is unnecessary when pre-produced yeast cell walls are used as the raw material. In the crude extraction step, for example, a hot water (including dilute alkali) extraction method (see, for example, Japanese Patent Publication No. 64-3479 and Japanese Patent Laid-Open No. 58-109423), an autolysis method (see, for example, Japanese Patent Publication No. 58-57153), or an enzymatic digestion method using a cell wall-lytic enzyme (see, for example, Japanese Patent Publication No. 59-40126) may be used. In the purification step, for example, protein removal treatment using hydrochloric acid or the like, alcohol precipitation treatment, protease treatment, chromatography treatment, etc. may be performed.

[0019] In this specification, crude yeast mannan extracts and purified yeast mannan products are collectively referred to as "yeast mannan preparations." The commercially available yeast mannans described above also fall under the category of yeast mannan preparations. In addition to yeast-derived α-mannan and / or yeast-derived α-mannan-protein complexes, the yeast mannan preparations may also contain various contaminants (e.g., glucans, proteins, mannose, etc.) that are present in the yeast cell wall or that are generated during the processing for preparing yeast mannan.

[0020] The yeast from which the yeast mannan is derived is not particularly limited as long as it has the above-mentioned α-mannan and the above-mentioned α-mannan-protein complex as constituent components of its cell wall. For example, the yeast may be the genus Saccharomyces, the genus Schizosaccharomyces, the genus Pichia, the genus Candida, the genus Kluyveromyces, Yeasts such as Williopsis, Debaryomyces, Galactomyces, Torulaspora, Rhodotorula, Yarrowia, or Zygosaccharomyces may be used, with Saccharomyces being preferred. The yeast from which the yeast mannan is derived may be either yeast that has been treated to incorporate minerals such as zinc, or yeast that has not been subjected to such treatment. Those skilled in the art can cultivate yeasts that are suitable for use as raw materials for preparing the yeast mannans that exhibit the effects of the present invention using standard methods and conditions. In other words, yeast cultured by a person skilled in the art according to common methods and conditions can be used as a raw material without any problems in preparing yeast mannan that exhibits the effects of the present invention.

[0021] In one embodiment, the yeast from which the yeast mannan is derived may be an edible yeast, preferably a yeast used as baker's yeast or brewer's yeast. Specifically, examples of yeasts from which the yeast mannan is derived include Saccharomyces cerevisiae, Schizosaccharomyces pombe, Saccharomyces pastorianus, Saccharomyces paradoxus, Saccharomyces mikatae, Saccharomyces bayanus, and Saccharomyces kudriavzevii. The bacterial strain may be one or more selected from the group consisting of Saccharomyces cerevisiae, Saccharomyces pastorianus, and / or Saccharomyces bayanus, and is preferably one or more selected from the group consisting of Saccharomyces cerevisiae, Saccharomyces pastorianus, Saccharomyces lactis, Candida utilis, Candida albicans, Candida tropicalis, Candida lipolytica, and Candida sake.

[0022] The content of yeast mannan in the yeast mannan preparation is not particularly limited and can be adjusted by appropriately selecting the method used in the crude extraction step, whether or not the purification step is performed, and, if the purification step is performed, the treatment method.A person skilled in the art can prepare a yeast mannan preparation containing a yeast mannan content that does not interfere with the achievement of the effects of the present invention using common methods and conditions.In other words, the yeast mannan preparation prepared by a person skilled in the art using common methods and conditions contains a yeast mannan content that does not interfere with the achievement of the effects of the present invention.

[0023] The content (ratio) of yeast mannan in the composition of the present invention or the yeast mannan preparation can be calculated as the total amount (α-mannan equivalent) of α-mannan and the α-mannan chain portion of the α-mannan-protein complex by the following method. For example, when determining the content (ratio) of yeast mannan in the yeast mannan preparation, first, the mannose in sample (A) of the yeast mannan preparation and the mannose in sample (B) obtained by hydrolyzing the yeast mannan preparation are each quantified. Here, sample (B) is obtained by treating sample (A) with sulfuric acid to hydrolyze all of the sugar chains in sample (A) into monosaccharides, followed by neutralization by conventional methods. The mannose in each sample can be quantified, for example, by high-performance liquid chromatography (HPLC), or may be quantified by the method implemented by the Japan Food Research Center. Next, the amount of mannose in sample (A) minus the amount of mannose in sample (B) is multiplied by 0.9 to subtract the amount of water bound by hydrolysis of α-mannan and the α-mannan chain portion, thereby calculating the yeast mannan content in the yeast mannan preparation in α-mannan equivalent. Finally, the proportion of yeast mannan in the yeast mannan preparation, i.e., the yeast mannan content, can be calculated in α-mannan equivalent by calculating the ratio of the yeast mannan content to the mass of sample (A).

[0024] The content of the yeast mannan in the composition of the present invention is not particularly limited and can be appropriately set taking into account the intake per meal or per day, but may be, for example, from about 0.05% to about 90% by mass, and preferably from about 0.05% to about 80% by mass, of the total mass of the composition, calculated as α-mannan. The daily intake of the yeast mannan is also not particularly limited, but may be, for example, from about 0.1 g to about 10.0 g, and preferably from about 0.1 g to about 6.5 g, calculated as α-mannan.

[0025] In one embodiment, the composition of the present invention may be in the form of a food, drink, or pharmaceutical, and can be appropriately prepared into a dosage form known as a food, drink, or pharmaceutical. The dosage form is not particularly limited, and may be, for example, a tablet, capsule, powder, granule, liquid, or other dosage form of a supplement (nutritional supplement), or may be a soft drink (carbonated drink, non-alcoholic drink, juice, coffee drink, tea drink, mineral water, sports drink, etc.), dairy drink, soy milk drink, fermented milk, lactic acid bacteria drink, cocoa, alcoholic drink (beer, happoshu, other brewed alcohol, liqueur, sake, amazake, wine, shochu, etc.), drink prepared from instant powder, or other drink, or bread, cereal, confectionery (biscuits, cookies, chocolate, etc.), processed food (bonito flakes, salted fish, kusaya, etc.), pickles (pickled vegetables in rice bran, kimchi, pickles, etc.), fermented food (natto, cheese, yogurt, etc.), seasoning (soy sauce, miso, vinegar, etc.), food additive (food emulsifier, food emulsion stabilizer, etc.), or other food.

[0026] Since the composition of the present invention is used to improve sleep quality, the composition may be labeled with, for example, the following: - For those who are dissatisfied with their sleep quality - For those who are dissatisfied with their sleep quality - Helps improve sleep quality (depth of sleep) - Improves sleep quality by increasing the ratio of deep sleep and REM sleep - Helps improve sleep quality (falling asleep) - Helps improve sleep quality (refreshed awakening) - Supports refreshed awakening - Helps improve sleep quality (depth of sleep when falling asleep) and refreshed awakening

[0027] There are no particular limitations on the subjects to which the composition of the present invention is applied, and it may be humans or other mammals (pets such as dogs and cats, and livestock such as pigs and cows).

[0028] The composition of the present invention may further contain any inactive ingredient commonly used in the art, such as a pharmaceutically or food-acceptable excipient, solvent, buffer, sweetener, acidulant, flavoring, antioxidant, etc., as long as it does not impair the objectives of the present invention. Furthermore, the composition may further contain an additional active ingredient commonly used in the art, as long as it does not impair the objectives of the present invention. The additional active ingredient may be an ingredient having a sleep-improving effect or may be an ingredient having another effect.

[0029] When the composition of the present invention is in the form of a food or beverage, it may further contain, in addition to the agents of the present invention, at least one selected from various components contained in common or well-known foods and beverages, such as water (or carbonated water), coffee extract, tea leaf extract, fruit juice, extracts of other plant materials, milk, soy milk, fermented milk, oils and fats, sugars, sweeteners, acidulants, coloring agents, and flavorings. The content of each agent of the present invention in the composition of the present invention is not particularly limited, and can be appropriately set, as in common compositions for foods and beverages, taking into consideration turbidity and the like, as necessary.

[0030] In another aspect, the present invention also relates to a method for improving sleep quality, comprising the step of administering an effective amount of yeast mannan to a subject, and the yeast mannan may be administered in the form of a composition for improving sleep quality described as one aspect of the present invention. In one aspect, the present invention also relates to a method for improving sleep quality, comprising the step of ingesting an effective amount of yeast mannan by a subject or having a subject ingest it. In other words, the present invention also relates to a method for improving sleep quality, comprising the step of introducing an effective amount of yeast mannan into the intestine of a subject. Specific aspects of the yeast mannan used in the method of the present invention and specific aspects of the sleep quality improved by the method of the present invention are as described above in relation to the composition of the present invention.

[0031] In another aspect, the present invention relates to the use of yeast mannan for the manufacture of a composition for improving sleep quality as described in one aspect of the present invention. Particular aspects of the yeast mannan used in the method of use of the present invention and particular aspects of the sleep quality improved by the composition defined by the present invention are as described above in relation to the composition of the present invention.

[0032] In another aspect, the present invention relates to a sleep quality improving agent comprising yeast mannan as an active ingredient, or a non-therapeutic use of yeast mannan as a sleep quality improving agent. Specific aspects of the yeast mannan used in the improving agent defined by the present invention and specific aspects of the sleep quality improved by the improving agent defined by the present invention are as described above for the composition of the present invention.

[0033] The present invention will be specifically explained below with reference to examples, but the scope of the present invention is not limited to these examples.

[0034] 1. Preparation of Yeast Mannan Preparation X (1) Yeast Mannan Preparation X: Derived from Saccharomyces pastorianus. 10 kg of commercially available yeast cell walls (trade name "Yeast Cell Wall", Asahi Group Foods Co., Ltd.) were suspended in distilled water, sodium hydroxide was added to adjust the pH to 11.0, and the suspension was boiled at 90°C for 12 hours. The supernatant was recovered by centrifugation, and hydrochloric acid was added to adjust the pH to 5.5. 2 kg of Yeast Mannan Preparation X was obtained by freeze-drying.

[0035] (2) Yeast Mannan Content The Japan Food Analysis Center, a general incorporated foundation, was commissioned to quantify the mannose in sample (A) of the yeast mannan preparation X obtained above, and in sample (B) obtained by hydrolysis of the yeast mannan preparation X obtained above. As a result, the mannose content of sample (A) was 0.17 g / 100 g of sample, and the mannose content of sample (B) was 61.3 g / 100 g of sample. Based on these values, the yeast mannan content in the obtained yeast mannan preparation X was calculated using the above-mentioned calculation method, and was found to be 55% in terms of α-mannan.

[0036] The specific procedure for quantifying mannose in specimens (A) and (B) at the Japan Food Research Center (General Incorporated Foundation) is as follows: 0.6 g of each specimen (A) and specimen (B) was collected, added to 72% sulfuric acid, and stirred at room temperature for 1 hour. The specimen solution was diluted to 4% sulfuric acid and then heated in an autoclave (121°C) for 1 hour. The specimen solution was cooled to room temperature, neutralized, and diluted to 200 mL with water. The quantified specimen solution was filtered through filter paper, and the filtrate was diluted 50-fold with water. The diluted solution was further filtered through a membrane filter. The filtrate was analyzed by high-performance liquid chromatography under the following operating conditions, and the mannose concentration in the filtrate was measured to quantify the mannose in specimens (A) and (B). Model: LC-20AD (Shimadzu Corporation) Detector: Fluorescence spectrophotometer RF-20Axs (Shimadzu Corporation) Column: TSKgel SUGAR AXI, φ4.6 mm × 150 mm (Tosoh Corporation) Column temperature: 60°C Mobile phase: 0.5 mol / L borate buffer (pH 8.7) Flow rate: 0.4 mL / min Injection volume: 20 μL Fluorescence excitation wavelength: 320 nm Fluorescence measurement wavelength: 430 nm Postcolumn: Reaction solution: 1 w / v% L-arginine solution Reaction solution flow rate: 0.7 mL / min Reaction temperature: 150°C

[0037] 2. Test Example 1: Tablets containing 90% by mass of yeast mannan preparation X were prepared as the test food, and tablets containing maltose instead of yeast mannan preparation X were prepared as the control food. A randomized, placebo-controlled, double-blind, parallel-group comparative study was conducted in which 33 healthy male and female volunteers ingested either the test food containing yeast mannan preparation X or a control food not containing yeast mannan preparation X for four consecutive weeks. Before and after the continuous intake, electroencephalograms during sleep were measured using an electroencephalograph to evaluate objective sleep state. The amount of yeast mannan preparation X in the test food ingested per day was 1130 mg, which corresponds to 0.62 g of α-mannan.

[0038] As a result, the total time spent in bed, from going to bed until getting up, did not change when the control food was consumed, but when the test food was consumed, the total time spent in bed increased, and the amount of change was significantly greater than the amount of change when the control food was consumed (Table 1).

[0039]

[0040] N3 (deep sleep), the deepest stage of non-REM sleep, is also known as slow-wave sleep and is believed to be associated with a sense of deep sleep. Deep sleep time was significantly increased in the test food group compared to the control food group (Table 2). The rate of deep sleep as a percentage of total sleep time (TST) (N3 / TST) also significantly increased in the test food group compared to the control food group (Table 2).

[0041]

[0042] Therefore, it was demonstrated that the intake of yeast mannan increases the time spent in bed and the duration and frequency of deep sleep. In other words, it was demonstrated that the intake of yeast mannan increases the duration of sleep and improves the feeling of deep sleep. Note that "total sleep time (TST)" refers to the time from falling asleep to the last awakening the next morning, excluding awakenings during the night.

[0043] The time from sleep onset to the first REM sleep (REM sleep latency) was significantly increased in the group that ingested the test food compared to the group that ingested the control food (Table 3).

[0044]

[0045] The time from falling asleep to the first deep sleep (deep sleep latency) was significantly shorter in the group ingesting the test food compared to the group ingesting the control food (Table 4), and the amount of change was also significantly different between the two groups (Table 4). Therefore, it was demonstrated that ingesting yeast mannan improves the ability to fall asleep and prolongs deep sleep.

[0046]

[0047] In addition, before the continuous intake of each food, 33 healthy men and women underwent a stress check using a 57-item Occupational Stress Assessment Questionnaire (see the "Implementation Manual for the Stress Check System Based on the Occupational Safety and Health Act" (revised February 2021) by the Industrial Health Support Office, Occupational Health Division, Occupational Safety and Health Department, Labor Standards Bureau, Ministry of Health, Labor and Welfare), and subjective sleep status was assessed using the Japanese version of the Pittsburgh Sleep Quality Index (PSQI). Fatigue was assessed on a 5-point scale based on the results of the 57-item Occupational Stress Assessment Questionnaire. Subjects were divided into those who were not aware of fatigue, who were judged to have "low" or "slightly low" fatigue, and those who were aware of fatigue, who were judged to have "normal," "slightly high," or "high" fatigue. There was no significant difference in the PSQI total score (mean ± standard error) between the study groups before intake of the food. However, the PSQI total score was higher in those who were aware of fatigue than those who were not (Table 5), suggesting that those who were aware of fatigue had poorer sleep quality.

[0048]

[0049] Subjects in each group who reported feeling fatigued were assessed for their subjective sleep status using the Japanese version of the PSQI even after continuing to consume each food. The PSQI total scores of subjects who reported feeling fatigued did not differ significantly before and after ingestion of the control food, but significantly decreased after ingestion of the test food (Figure 1A). The magnitude of change was significantly different between the control food and test food groups (Figure 1B). Furthermore, the daytime wakefulness score, a PSQI item, significantly decreased only in the test food group (Figure 2). Therefore, it was demonstrated that ingestion of yeast mannan improved sleep quality and reduced daytime sleepiness.

[0050] 3. Test Example 2: Tablets containing 90% by mass of yeast mannan preparation X were prepared as the test food, and tablets containing maltose instead of yeast mannan preparation X were prepared as the control food. A randomized, placebo-controlled, double-blind, parallel-group comparative study was conducted in which 100 healthy male and female subjects continuously ingested either the test food containing yeast mannan preparation X or the control food not containing yeast mannan preparation X for 8 weeks. Before and after continuous intake, electroencephalography (EEG) measurements during sleep were used to measure objective sleep status. Sleep efficiency was calculated as TST / TIB (%), calculated by dividing total sleep time (TST) by total time in bed (TIB). Subjective sleep status was also evaluated before and after continuous intake using the Pittsburgh Sleep Quality Index (PSQI) Japanese version and the OSA Sleep Questionnaire MA version. The amount of yeast mannan preparation X in the test food to be ingested per day was 1130 mg, which is equivalent to 0.62 g of α-mannan.

[0051] The results showed that there was no significant difference in the PSQI total score between the test and control food groups before ingestion, but after ingestion, the PSQI total score of the test food group was significantly lower than that of the control food group, and the amount of change was also significantly different between the two groups (Table 6).In addition, the amount of change in the sleep time score, one of the PSQI items, was significantly different between the two groups, with a decrease in the score being observed in the test food group (Table 7).

[0052]

[0053]

[0054] For both the PSQI total score and sleep duration score, lower scores indicated a better state, demonstrating that yeast mannan intake improved sleep duration and overall sleep quality.

[0055] Regarding the second factor (initiation and maintenance of sleep) of the MA version of the OSA Sleep Questionnaire, no significant differences were observed between the test food group and the control food group before ingestion. However, the scores of the test food group after ingestion were significantly higher than those of the control food group, and the amount of change was also significantly different between the two groups (Table 8).

[0056]

[0057] The second factor of the OSA Sleep Questionnaire MA version indicates a good state with a higher score, demonstrating that yeast mannan intake improves sleep onset and sleep maintenance.

[0058] The change in sleep efficiency calculated from EEG measurements was significantly different between the two groups, with the test food group showing higher values ​​than the control food group after ingestion (Table 9).In addition, the change in total continuous wakefulness time (the total time during which wakefulness lasted for 3 minutes (6 epochs) or more) was significantly different between the two groups, with the test food group showing lower values ​​than the control food group after ingestion (Table 10).

[0059]

[0060]

[0061] Therefore, it was demonstrated that yeast mannan intake reduces the time spent awake during the night and leads to more efficient sleep.

[0062] These findings suggest that ingesting yeast mannan can improve sleep quality. Because yeast mannan is used as a food ingredient and can be ingested daily, it is possible to improve the quality of sleep and thereby improve the quality of life.

Claims

1. A composition for improving sleep quality, comprising yeast mannan.

2. The composition according to claim 1 for improving at least one selected from the group consisting of depth of sleep, falling asleep, sleepiness, sleep time, sleep efficiency, and awakening during sleep.

3. The composition according to claim 1, wherein the content of the yeast mannan is from 0.05% by mass to 90% by mass in terms of α-mannan based on the total mass of the composition.

4. The composition according to claim 1, wherein the daily intake amount of the yeast mannan is from 0.1 g to 10.0 g in terms of α-mannan.

5. The composition according to any one of claims 1 to 4, which is in the form of a food or drink.

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