Distal Skin Temperature Pattern for Sleep Timing

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Solution Overview

Problem

Current methods for monitoring sleep cycles are impractical, uncomfortable, and prone to interference, as they rely on core temperature measurements or noisy movement data, which are not always accurate or convenient.

Innovation Solution

Monitoring distal skin temperature patterns, which correlate with melatonin production, to determine optimal sleep and wake-up times, using a method that detects a rapid temperature drop followed by a rise, indicating a distinct pattern within the circadian rhythm.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If core temperature measurement is used to monitor sleep cycles, then measurement accuracy is improved, but practicality and comfort deteriorate

Engineering Contradiction:
Improvesleep cycle detection accuracyVSAvoidmeasurement practicality
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent uses distal skin temperature as an intermediary measurement that correlates with core temperature and circadian rhythm without requiring invasive core temperature measurement. The distal skin temperature serves as a mediator that provides sufficient information about sleep cycles while being much more practical and comfortable to measure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical/invasive approach of core temperature measurement with a non-contact or minimal-contact optical/infrared detection method for measuring distal skin temperature, thereby improving comfort and practicality while maintaining sufficient measurement accuracy.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If movement sensors are used to estimate sleep cycles, then ease of operation is improved, but measurement reliability deteriorates due to interference and positioning dependence

Engineering Contradiction:
Improvesensor operation simplicityVSAvoidsleep cycle detection reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent replaces mechanical movement sensors with thermal sensing based on distal skin temperature changes. This substitution eliminates the problems of movement sensor interference and positioning dependence, as temperature measurement is not affected by ambient movement or sensor placement variations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the measurement parameter from mechanical movement to thermal properties (distal skin temperature). This parameter change fundamentally improves reliability by measuring a physiological parameter that is intrinsic to the sleep-wake cycle and circadian rhythm, rather than relying on external movement patterns that are prone to interference.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If high-precision temperature measurement is used to detect temperature change patterns, then detection accuracy is improved, but device complexity and cost increase

Engineering Contradiction:
Improvetemperature change detection accuracyVSAvoidmeasurement system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the measurement parameter from core temperature to distal skin temperature, which exhibits more pronounced and faster temperature changes during circadian rhythm transitions. This parameter change allows for accurate detection of sleep onset and cycle progression using simpler, lower-cost temperature sensors rather than requiring high-precision core temperature measurement systems.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

Instead of measuring core temperature directly (the traditional approach), the patent inverts the approach by measuring distal skin temperature, which shows more distinct and rapid temperature patterns. This inversion allows for accurate sleep cycle detection using less complex measurement systems.

Inventive Principle:
Principle #13The other way round (Inversion)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for accurate, comfortable, and robust determination of sleep cycles, enabling optimal sleep timing and wake-up instants without the need for precise temperature measurement, using low-cost equipment like MEMS or infrared sensors.

Implementation Method 1

Sleep of a human follows a circadian rhythm, i.e. a sleep-wakefulness cycle that is on average 24.09 ± 0.2 h (24 h 5 min ± 12 min) for women and 24.19 ± 0.2 h (24 h 11 min ± 12 min) for men, aged 18 to 74 years.

Methodology Applied
Scientific EffectCircadian rhythm:

Implementation Method 2

There is a direct link between production of melatonin (and other hormones related to sleep) and the circadian rhythm. Once the level of melatonin in the blood stream of the person reaches a certain level after start of nocturnal melatonin production, a rapid, distinct pattern can be observed in the distal skin temperature of the person.

Methodology Applied
Scientific EffectMelatonin production:

Data Source

PatentEP3503794B1Method and system for determining time window for sleep of a person
Publication Date: 2020.07.01 NIGHT TRAIN OY
  • EP3503794B1 patent drawingFigure 1

AI summary

The present disclosure describes a method and a system implementing the method for determining an optimal time window for sleep of a person. The method comprises receiving samples of a distal skin temperature of the person, and detecting a temperature change pattern in the samples of distal skin temperature. The temperature change pattern indicates a reference point within the circadian rhythm. The optimal time window for sleep is determined on the basis of the indicated reference point. The temperature change pattern is in the form of a drop in the distal skin temperature followed an increase in the distal skin temperature, where the drop and the increase occur within a time window of ten minutes or less.