Although a nocturnal rise in PRL secretion is well known, it has long been presumed to be evoked by sleep. To determine whether PRL secretion was driven by a sleep-independent circadian rhythm, we studied 12 men and 10 women using a constant routine protocol. Under the constant routine conditions of continuous semirecumbent wakefulness in constant indoor room light with hourly meals distributed...

Automated monitoring of circadian rhythms is an efficient way for gaining insight into oscillation parameters like period and phase for the underlying pacemaker of the circadian clock. Measurement of the circadian rhythm of phototaxis (swimming towards light) exhibited by the green alga Chlamydomonas reinhardtii has been automated by directing a narrow and dim light beam through a culture at re...

Everyone has their own circadian rhythm, which is in various stages of life influenced by many different influences. Seniors and other people with disabilities tend to have circadian rhythms much more regular than the rest of the population. In the case of an effective way of detecting circadian rhythms, their interpretation and subsequent detection of deviations and abnormalities can deduce no...

A growing body of research has identified significant sleep problems in children with autism. Disturbed sleep-wake patterns and abnormal hormone profiles in children with autism suggest an underlying impairment of the circadian timing system. Reviewing normal and dysfunctional relationships between sleep and circadian rhythms will enable comparisons to sleep problems in children with autism, pr...

Experimental data show a close relationship among melatonin, circadian rhythms, and sleep. Low-dose melatonin treatment, increasing circulating melatonin levels to those normally observed at night, promotes sleep onset and sleep maintenance without changing sleep architecture. Melatonin treatment can also advance or delay the phase of the circadian clock if administered in the evening or in the...

The sleep-wake cycle displays a characteristic 24-hour periodicity, providing an opportunity to dissect the endogenous circadian clock through the study of aberrant behaviour. This article surveys the properties of circadian clocks, with emphasis on mammals. Information was obtained from searches of peer-reviewed literature in the PUBMED database. Features that are highlighted include the known...

A central mechanism for controlling circadian gene amplitude remains elusive. We present evidence for a "facilitated repression (FR)" model that functions as an amplitude rheostat for circadian gene oscillation. We demonstrate that ROR and/or BMAL1 promote global chromatin decondensation during the activation phase of the circadian cycle to actively facilitate REV-ERB loading for repression of ...

The circadian clock is a molecular network of genes and proteins that control biological timing. In the suprachiasmatic nucleus of the brain, this unique signaling pathway operates to control the 24-hour sleep-wake cycle. In the periphery, the circadian clock acts to regulate local functions that follow circadian rhythms. Indeed, the cardiovascular system of mammals follows a circadian rhythm, ...

BACKGROUND Recently, we found that sodium restriction shifted the circadian rhythm of blood pressure from nondipper to dipper in patients with the sodium-sensitive essential hypertension. This study examined whether diuretics can transform the circadian rhythm of blood pressure from nondipper to dipper. METHODS AND RESULTS We studied 21 patients with essential hypertension during both a basel...