Sleep and circadian rhythms in humans.
Level 5 - mechanism / opinion, no new human data
Narrative review of human circadian physiology and sleep regulation.
PubMed 18419318 · doi:10.1101/sqb.2007.72.064
What was done
This paper reviews five decades of physiological and molecular findings on the fundamental properties of the human circadian timing system, light-induced phase resetting, multi-oscillator organization, and interactions between the circadian pacemaker and homeostatic sleep regulation.
What was found
The intrinsic circadian period in sighted humans is reported to be tightly distributed around approximately 24.2 hours, exhibiting aftereffects of prior entrainment. Light is identified as the primary synchronizer capable of producing weak (Type 1) or strong (Type 0) phase resetting depending on intensity and timing. In addition, circadian photoreception can be preserved in blind individuals lacking conscious sight and adapts based on prior light history. No other specific quantitative figures or effect sizes are provided in the abstract.
Why it matters
Understanding the multi-oscillator circadian architecture and its interaction with homeostatic sleep drive provides the mechanistic foundation for managing shift work, jet lag, and clinical circadian sleep-wake disorders.
Limits
The abstract describes a narrative review without systematic search criteria, defined inclusion parameters, or pooled meta-analytic data. Specific participant counts, demographics, and clinical outcome metrics are not reported.
Cited by
- supports The human intrinsic circadian clock generates an intrinsic rhythm of approximately 24.2 or 24.3 hours.