CHRONO-EXERCISE CONSOLIDATES SLEEP

Circadian rhythms are the biological process that helps to regulate the sleep-wake cycle. These rhythms are regulated by the suprachiasmatic nucleus (SCN) located in the anterior hypothalamus in the brain. Disrupted circadian rhythms can lead to sleep disturbances and poor sleep habits over time. PURPOSE: The purpose of this study is to use exercise as a method of re-entraining circadian rhythms in mice through forced treadmill running and sleep analysis. METHODS: This work was approved by the University of Wyoming IACUC. In this study we took male (n=8) and female mice (n=4) and studied their sleep rhythm during exercise entrainment. The sleep system was non-invasive and continuously monitored the mice for seven days pre-exercise and seven days during exercise. The exercise training protocol mimicked ACSM guidelines for moderate intensity and was as follows: Days 1 – 7 warm –up at 8m/min for 5 minutes then 13 m/min for 35 minutes. Exercise occurred 30 minutes after lights off for males and females. RESULTS: Male mice had more consolidated sleep with early active period exercise as shown through increased bout length, total sleep, dark period sleep, and the decreased number of bouts. Late active period exercise was also done with male mice and results showed that the total bout length and day sleep decreased suggesting that exercise at this time does not carry the same benefits as early exercise. Females respond differently than males in most instances but responded similarly to early chrono-exercise with an increase in sleep and sleep duration. CONCLUSION: Exercise is a viable and cost-effective method to help with sleep. It is a natural way to regulate the circadian rhythm, promoting deeper and more restful sleep. Continuation of this work will shed light to the neural mechanisms underlying how sleep is consolidated in exercised entrained mice.