Dijk, Derk-Jan, and Steven W. Lockley. Invited Review: Integration of human sleep-wake regulation and circadian rhythmicity. J Appl Physiol 92: 852–862, 2002; 10.1152/japplphysiol.00924.2001.—The human sleep-wake cycle is generated by a circadian process, originating from the suprachiasmatic nuclei, in interaction with a separate oscillatory process: the sleep homeostat. The sleep-wake cycle is...

The wake-sleep rhythm is a typical circadian rhythm. It has been reported that severely disturbed wake-sleep rhythms are improved by the administration of vitamin B12. This study was designed to clarify whether vitamin B12 is universally related to the circadian rhythm. Three-week-old male Wistar Kyoto rats were fed a vitamin B12 deficient diet for 3 months. Then some of them were given intrape...

BACKGROUND: There is accumulated evidence that plasma concentration of the sulfur-containing amino-acid homocysteine (Hcy) is a prognostic marker for cardiovascular morbidity and mortality. Both fasting levels of Hcy and post methionine loading levels are used as prognostic markers. The aim of the present study was to investigate the existence of a daily rhythm in plasma Hcy under strictly cont...

Evidence that the sleep-wake rhythm is generated endogenously has been provided by studies employing a variety of experimental paradigms such as sleep deprivation, sleep displacement, isolating subjects in environments free of time cues, or imposing on subjects sleep-wake schedules widely deviating from 24 hours. The initial observations obtained in isolated subjects revealed that the period of...

The human sleep-wake cycle is generated by a circadian process, originating from the suprachiasmatic nuclei, in interaction with a separate oscillatory process: the sleep homeostat. The sleep-wake cycle is normally timed to occur at a specific phase relative to the external cycle of light-dark exposure. It is also timed at a specific phase relative to internal circadian rhythms, such as the pin...

Sleep is a behavioral process that is governed by both homeostatic and circadian processes. While the intensity and duration of sleep is governed mainly by the homeostatic process (sleep debt), the timing of sleep is orchestrated by the anterior hypothalamic suprachiasmatic nuclei (SCN). Disturbances in the organization of the sleep/wake cycle as well as circadian (approximately 24-hour periodi...

Early neuropathological changes characteristic of late-onset Alzheimer's disease (LOAD) involve brain stem and limbic structures that regulate neurovegetative functions, including sleep-wake rhythm. Indeed, sleep pattern is an emerging biomarker and a potential pathophysiological mechanism in LOAD. We hypothesized that cognitively asymptomatic, middle-aged offspring of patients with LOAD (O-LOA...