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The phase response curve for melatonin is roughly twelve hours out of phase with the phase response curve for light. [9] At spontaneous wake-up time, exogenous (externally administered) melatonin has a slight phase-delaying effect. The amount of phase-delay increases until about eight hours after wake-up time, when the effect swings abruptly ...
[43] [44] Prolonged-release melatonin is safe with long-term use of up to 12 months. [11] Although not recommended for long-term use beyond this, [45] low-dose melatonin is generally safer, and a better alternative, than many prescription and over-the-counter sleep aids if a sleeping medication must be used for an extended period of time.
Recently, ultradian rhythms of arousal lasting approximately 4 hours were attributed to the dopaminergic system in mammals. [5] When the dopaminergic system is perturbed either by use of drugs or by genetic disruption, these 4-hour rhythms can lengthen significantly into the infradian (> 24 h) range, sometimes even lasting for days (> 110 h ...
The possible causes of non-24-hour sleep-wake disorder are 2-fold: (1), extrinsic: isolation from daily light cycles (such as working in an environment completely devoid of natural lighting); [citation needed] and (2), intrinsic: where some condition, such as blindness or malfunctioning biochemical response to light in the subject, prevent ...
A person's chronotype is the propensity for the individual to sleep at a particular time during a 24-hour period. Eveningness (delayed sleep period; most active and alert in the evening) and morningness (advanced sleep period; most active and alert in the morning) are the two extremes with most individuals having some flexibility in the timing ...
[1] 6-Hydroxymelatonin is produced as a result of the enzymatic conversion of melatonin through hydroxylation. [2] Similar to melatonin, 6-OHM is a full agonist of the MT 1 and MT 2 receptors. [3] [4] It is also an antioxidant and neuroprotective, and is even more potent in this regard relative to melatonin. [5] [6]
As sleep time decreased over time from the 1950s to 2000s from about 8.5 hours to 6.5 hours, there has been an increase in the prevalence of obesity from about 10% to about 23%. [2] Weight gain itself may also lead to a lack of sleep as obesity can negatively affect quality of sleep, as well as increase risk of sleeping disorders such as sleep ...
Large doses of melatonin can even be counterproductive: Lewy et al. [48] provide support to "the idea that too much melatonin may spill over onto the wrong zone of the melatonin phase-response curve." The long-term effects of melatonin administration have not been examined. In some countries, the hormone is available only by prescription or not ...