Human circadian melatonin rhythm phase delay during a fixed sleep–wake schedule interspersed with nights of sleep deprivation

Abstract

The human circadian pacemaker, with an intrinsic period between 23.9 and 24.5 hr, can be reset by low levels of light. Biomathematical models of the human clock predict that light-dark cycles consisting of only approximately 3.5 lux during 16 hr of wakefulness and 0 lux during 8 hr of sleep should entrain approximately 45% of the population. However, under real-life conditions, sleep-wake schedules and the associated light-dark exposures are often irregular. It remains unclear whether the phase of the pacemaker would remain stable under such conditions. We investigated the stability of the circadian phase in dim light by assessing the plasma melatonin rhythm during nine consecutive circadian cycles. Ten subjects were scheduled to sleep for 8 hr (0.03 lux) and to be awake for 16 hr (5-13 lux) during all days except on days 4 and 8, during which the subjects were sleep deprived for 40 hr (5-13 lux), either in a sitting/standing or supine body posture. In all subjects, the phase of the melatonin rhythm occurred at a later clock time on day 9 than on day 2 (average delay: 1.4 hr). Largest delays in the melatonin onset were observed in subjects with low amplitude melatonin rhythms. The area under the curve during active melatonin secretion was significantly reduced when subjects were sleep deprived in the 40-hr supine body posture condition compared with either the 40-hr sitting/standing sleep deprivation (SD) or the ambulatory condition under non-SD conditions. Posture differences did not significantly affect the relative phase position of the melatonin profiles. The data indicate that under conditions of reduced zeitgeber strength, the phase of the human circadian pacemaker, using plasma melatonin as a marker, can be phase delayed by one night of SD and the associated dim light exposure.

Effect of sleep deprivation on rhythms of clock gene expression and melatonin in humans

“…Further in agreement with the current data, a phase delay in the melatonin rhythm has previously been reported after one night of sleep deprivation (Cajochen et al, 2003), and an increase in melatonin levels was found in young subjects during extended wakefulness (up to 50 h) (Zeitzer et al, 2007). The latter study, however, also described an age-dependent difference in melatonin profiles, with young subjects exhibiting reduced and older subjects exhibiting elevated melatonin levels during one night of sleep deprivation compared to habitual sleep.…”

Melatonin Entrains Free‐running Blind People According to a Physiological Dose‐response Curve

“…The finding of previous studies (Voultsios et al, 1997;Cajochen et al, 2003) indicates posture does not appear to affect the MO. Blood was drawn through an intravenous saline-lock, usually placed in the forearm.…”

Adaptation rate of 6-sulfatoxymelatonin and cognitive performance in offshore fleet shift workers: a field study

“…The role of light exposure is determined by a number of parameters, such as light intensity, and duration and pattern of exposure (Sack et al 2007). Our measurements showed light intensities that ranged between 3 and 243 lux at night in the ship's compartments and it has been suggested that even dim light of 5-13 lux may slightly suppress melatonin (Cajochen et al 2003). Light intensity did not vary in the ship's working areas, and the duration of exposure lasted for the whole shift, i.e., 12 h, interrupted only by meal breaks and operation halts.…”