Body Clocks - Coordination of Peripheral and Central Oscillators

The investigators are conducting an observational trial examining young women over the course of 28 days in which we are monitoring movement, sleep, heart rate, oxygen saturation, gut physiology, light, and menstrual cycle. The inter- and independence of the cyclicity of these variables with each other, the circadian cycle, the menstrual cycle, and the sleep cycle will be tested.

For 28 days, women will wear devices to capture: ambient light exposure, lower limb biomechanics, sleep, oxygen saturation, heart rate, temperature, and gut physiology. Twice during the study, women will have saliva collected for 7 hours under dim light conditions in order to determine melatonin concentrations. During this 7-hour period, two blood draws for determination of proteomic profiles will also occur. Daily urine samples will be tested for LH until the presence of the LH surge to help identify menstrual phase.

Inclusion Criteria: * Regular menstrual cycle (21-35 days) * 18-30 years old Exclusion Criteria: * Neuromuscular or neurodegenerative disease * Gut disorders * circadian sleep disorders * prescription medications affecting sleep * recovering from physical injury * taking hormonal birth control