Personalised daily body-clock tracking using wearables sensors

This pilot trial aims at testing and refining the first high performance hybrid wearable-sensor integrated with circadian physiology and data driven analysis methods needed for daily circadian rhythm tracking in healthy adult sleepers and adults with sleep disorders. Participants will be wearing wrist-, chest-, and neck-worn monitors to capture a range of physiological signals, such as skin and core body temperature, physical activity, heart rate, and ambient light exposure data in 3 days (72 hours). They will be provided with a mattress and bedside sensor and monitoring device which will be placed on their mattresses to capture body position and breathing signals while asleep. Participants will ingest capsules which contain a temperature sensor and a wireless transmitter to record core body temperature (about 1 capsule ingested per day). They will also be asked to log their sleep and activities while at home and complete smartphone-administered cognitive performance tests each morning and evening during this time. On the third day of the trial, participants will collect saliva samples for dim light melatonin onset (DLMO) assessment, with appropriate instructions provided by the research team beforehand. Serial salivary samples will be collected every 30 minutes by participants themselves in dimly lit home environment from 5 hours before to 2 hours after their normal bedtime, i.e., 7 hours in total. DLMO assessment is the gold standard for measuring circadian timing and will be used as a comparison against the core body temperature data collected by the wearable devices. To assess adherence, we will review participants' daily usage of devices and their daily logs of sleep and activities, and examine the degree of data loss from each device and the integrity of the physiological signals they collect. Similarly, the completion rate of the cognitive performance tasks will be assessed. Data generated will be used to refine current analytical methods to separate small circadian from much larger activity and exercise effects on core body temperature.