Exercise elicits phase shifts and acute alterations of melatonin that vary with circadian phase

Abstract

Buxton, Orfeu M., Calvin W. Lee, Mireille L'HermiteBalé riaux, Fred W. Turek, and Eve Van Cauter. Exercise elicits phase shifts and acute alterations of melatonin that vary with circadian phase. Am J Physiol Regul Integr Comp Physiol 284: R714-R724, 2003; 10.1152/ajpregu. 00355.2002To examine the immediate phase-shifting effects of high-intensity exercise of a practical duration (1 h) on human circadian phase, five groups of healthy men 20-30 yr of age participated in studies involving no exercise or exposure to morning, afternoon, evening, or nocturnal exercise. Except during scheduled sleep/dark and exercise periods, subjects remained under modified constant routine conditions allowing a sleep period and including constant posture, knowledge of clock time, and exposure to dim light intensities averaging (ϮSD) 42 Ϯ 19 lx. The nocturnal onset of plasma melatonin secretion was used as a marker of circadian phase. A phase response curve was used to summarize the phaseshifting effects of exercise as a function of the timing of exercise. A significant effect of time of day on circadian phase shifts was observed (P Ͻ 0.004). Over the interval from the melatonin onset before exercise to the first onset after exercise, circadian phase was significantly advanced in the evening exercise group by 30 Ϯ 15 min (SE) compared with the phase delays observed in the no-exercise group (Ϫ25 Ϯ 14 min, P Ͻ 0.05). Phase shifts in response to evening exercise exposure were attenuated on the second day after exercise exposure and no longer significantly different from phase shifts observed in the absence of exercise. Unanticipated transient elevations of melatonin levels were observed in response to nocturnal exercise and in some evening exercise subjects. Taken together with the results from previous studies in humans and diurnal rodents, the current results suggest that 1) a longer duration of exercise exposure and/or repeated daily exposure to exercise may be necessary for reliable phase-shifting of the human circadian system and that 2) early evening exercise of high intensity may induce phase advances relevant for nonphotic entrainment of the human circadian system. jet lag; shift work DURING THE PAST decade, studies in several rodent species have shown that nonphotic stimuli are capable of altering mammalian circadian rhythms. Perturbation analyses of the circadian locomotor rhythms of nocturnal rodents revealed that exposure to single nonphotic stimuli, such as pulses of induced activity during constant darkness (25,26,28,31) or pulses of darkness during constant light, which also induce increased activity (7, 16), results in phase shifts that are dependent on the timing of stimulus presentation. Detailed studies of the nonphotic component of the rodent circadian system have led to an understanding of the types of stimuli that lead to phase shifts and/or alterations of photic entrainment, as well as model systems for examining the neural pathways and genes involved in these processes.In contrast, the nonphotic component of the...

Exercise and sleep - Review and future directions

“…The phase response curve of exercise on the human circadian pacemaker was reported by Buxton et al 23) . Their data indicated that evening exercise induced a phase advance and night exercise induced phase delay; morning and afternoon exercise had no effect on the circadian phase.…”

Sincronização não-fótica: o efeito do exercício físico aeróbio

“…Klerman et al (1998) (21) found a phase advance when the PE was performed 6 hours after wake up time. Buxton et al (2003) (18) also verified an advance. However, the PE was performed at the beginning of the night, about 6:30 p.m.…”

“…There is massive evidence that PE may act as a non-photic synchronizer, being able to dislocate the circadian rhythms phase (17)(18)(19)(20)(21)(22)(23)(24) . This phenomenon may be observed when PE is applied in constant situations, in which the influence of other synchronizers both photic and non-photic are tried to be blocked.…”

“…Usually, in the studies in which PE was applied between the middle and the ending of the nocturnal phase, the researchers found a phase delay (17)(18)(19)(20)22,24) . When PE was performed both in the morning and in the afternoon, it was possible to verify a phase advance in a study (20) .…”

Human circadian rhythms and exercise: Significance and application in real-life situations

“…Basic studies [62][63][64][65] to elucidate the acute phaseshifting effects of exercise measured parameters revealing the human body clock such as plasma melatonin and core body temperature for two to three successive days under a controlled situation to exclude the masking effects of 311 JPFSM : Human circadian rhythms and exercise behavior and environment. Other studies examined the effects of exercise when the sleep time of the subjects was delayed [66][67][68] or advanced [69][70][71][72] .…”