Phase-adjustment of human circadian rhythms by light and physical exercise

Abstract

The human circadian system derives from two distinct circadian oscillators that separately regulate circadian rhythms of body temperature and plasma melatonin, and of the sleep-wake cycle. The oscillator for body temperature and melatonin is the central circadian pacemaker, located in the hypothalamic suprachiasmatic nucleus (SCN), and the oscillator for sleep-wake cycle is another oscillator, located in the brain but outside the SCN. Although bright light is a primary zeitgeber for circadian rhythms, non-photic time cues such as a strict sleep schedule and timed physical exercise act as a non-photic zeitgeber for the sleep-wake cycle under dim light conditions, independent on the SCN circadian pacemaker. Recently, timed physical exercise under bright light has been shown to accelerate re-entrainment of circadian rhythms to an advanced sleep schedule. Physical exercise may enhance the phase-shift of circadian rhythm caused by bright light by changing light perception. In the field of sports medicine and exercise science, adjustment of the circadian rhythm is important to enable elite athletes to take a good sleep and enhance exercise performance, especially after inter-continental travel and jet lag.

Advancing Research on Care Needs and Supportive Approaches for Persons With Dementia: Recommendations and Rationale

“…41,42 Emerging research suggests that consistent timing of these activities may program anticipatory rhythms and synchronize circadian patterns. 43,44…”

Effects of exercise on circadian rhythms in humans

“…In the study simulating advanced jet lag, the time of exercise was set in the morning and the middle of the night, which may include both advance and delayed regions of the phase-response curves (PRC) ( Yamanaka et al, 2014 ). As a result, the advanced shift of circadian rhythms in bright light may be due to exercise enhancing the entrainment of light to the circadian rhythm by regulating the 5-HT (5-hydroxytryptamine) system ( Cymborowski, 1998 ; Mistlberger et al, 2010 ) or enhancing the light-sensing ability of the circadian system ( Yamanaka and Waterhouse, 2016 ), which induced a larger advanced shift ( Figure 2 ).…”

“…As a nonphotic zeitgeber, regular exercise entrains the circadian rhythms at the The entrainment of circadian rhythms by light and exercise. The central clock oscillator, which regulates rhythms of melatonin and body temperature, is located within the suprachiasmatic nucleus (SCN), while oscillators governing the sleep-wake cycle may exist in brain regions beyond the SCN (Yamanaka and Waterhouse, 2016;Yamanaka, 2020). Two potential pathways for entraining the central circadian rhythm through exercise are depicted: 1, exercise entrains the central clock directly; 2, exercise entrains oscillators in extra-SCN brain regions, which then transmit signals to the SCN.…”

Ramelteon for Delayed Sleep-wake Phase Disorder: A Case Report

“…Delayed sleep-wake phase disorder (DSWPD) is a circadian rhythm disorder characterized by persistent inability to fall asleep and wake up at conventional times. Treatment for DSWPD requires a multifactorial approach, including pharmacotherapy [1][2][3][4], chronotherapy [5], bright light therapy [6], and intervention with zeitgeber [7,8]. According to the current literature, melatonin is the preferred drug treatment for DSWPD [9].…”