Research

Hormonal

The endogenous circadian pacemaker significantly modulates sleep propensity, with sleep latency being shortest (highest propensity) when sleep coincides with the minimum of the core body temperature rhythm, and longest (lowest propensity) when it coincides with the maximum.

To fall asleep faster, try to align your bedtime with your body's natural temperature minimum, which typically occurs in the early morning hours (e.g., 4-6 AM) for most people. If you must sleep at other times, expect longer sleep latency. Consistent sleep-wake times help stabilize this rhythm.

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Sleep latency varied significantly with the phase of the endogenous circadian rhythm (Fig. 2E). Minimum latencies were observed in the interval 165°-195°. Maximum latencies were observed at the minimum component of the temperature rhythm, which corresponded to the interval between 22:00 hr and 06:00 hr.
Derk‐Jan Dijk et al. · Journal of Neuroscience · 1995

Why this rating

High-quality experimental design using forced desynchrony protocol in healthy humans, allowing separation of circadian and homeostatic components.

Source

Contribution of the circadian pacemaker and the sleep homeostat to sleep propensity, sleep structure, electroencephalographic slow waves, and sleep spindle activity in humans

Derk‐Jan Dijk et al. · Journal of Neuroscience · 1995

DOI 10.1523/jneurosci.15-05-03526.1995

rct · n=8Cited 1,346×
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DOI resolved against Crossref · corpus check 2026-06-10

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