# Temperature & air: what the research actually says

Sleep starts with a fall in core temperature, so the room's job is to let heat leave your body.



## All studies

- **Nighttime ambient temperature and sleep in community-dwelling older adults** — Baniassadi A, Manor B, Yu W, Travison T, Lipsitz L (2023), Science of the Total Environment 899:165623. Sleep efficiency was best between ~20–25 °C (68–77 °F) in older adults and dropped 5–10% as rooms warmed — cooler is better, personal range matters.

- **The temperature dependence of sleep** — Harding EC, Franks NP, Wisden W (2019), Frontiers in Neuroscience 13:336. Falling core temperature (via warm skin, cool room) is a trigger for sleep onset.

- **Effects of thermal environment on sleep and circadian rhythm** — Okamoto-Mizuno K, Mizuno K (2012), Journal of Physiological Anthropology 31(1):14. Heat exposure increases wakefulness and reduces deep and REM sleep; humidity worsens it.

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Educational summary of published research, not medical advice. Screening scores are not diagnoses. If a score is elevated or you feel unwell, talk to a clinician.

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