Bedroom temperature

Practical note

Graded low: the 2024 systematic review synthesised observational real-world studies without pooling, and the mechanistic support comes from small laboratory studies summarised in a narrative review; the direction is consistent across both, which keeps it above very low.

Sources

• Supports“We show that higher outdoor or indoor temperatures are generally associated with degraded sleep quality and quantity worldwide.” (Abstract) Chevance G, Minor K, Vielma C, Campi E, O'Callaghan-Gordo C, Basagaña X, Ballester J, Bernard P. 2024. Sleep Medicine Reviews. A systematic review of ambient heat and sleep in a warming climate. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine
• Supports“In real-life situations where bedding and clothing are used, heat exposure increases wakefulness and decreases slow wave sleep and rapid eye movement sleep.” (Abstract) Okamoto-Mizuno K, Mizuno K. 2012. Journal of Physiological Anthropology. Effects of thermal environment on sleep and circadian rhythm. CC BY; credit Okamoto-Mizuno and Mizuno, Journal of Physiological Anthropology 2012; Courtesy of the U.S. National Library of Medicine

Practical note

Graded low: one longitudinal home-monitoring cohort and one small controlled exposure study (16 participants over 65), consistent with the systematic review; downgraded for imprecision and the observational design of the cohort. The cohort reported a 5 to 10 percent drop in sleep efficiency between 25 and 30 °C, with substantial differences between participants.

Safety note

The systematic review reports a stronger effect of heat on sleep in vulnerable populations.

Sources

• Supports“Our findings demonstrated that sleep was most efficient and restful when nighttime ambient temperature ranged between 20 and 25 °C, with a clinically relevant 5-10 % drop in sleep efficiency when the temperature increased from 25 °C to 30 °C.” (Abstract) Baniassadi A, Manor B, Yu W, Travison T, Lipsitz L. 2023. Science of the Total Environment. Nighttime ambient temperature and sleep in community-dwelling older adults. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine
• Supports“The results showed that at the temperature of 30°C, the total sleep time, sleep efficiency, and duration of REM sleep of the elderly decreased by 26.3 min, 5.5%, and 5.3 min, respectively, and time awake increased by 27.0 min, in comparison with 27°C” (Abstract) Yan Y, Zhang H, Kang M, Lan L, Wang Z, Lin Y. 2022. Indoor Air. Experimental study of the negative effects of raised bedroom temperature and reduced ventilation on the sleep quality of elderly subjects. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine
• Context“The negative effect of heat persists across sleep measures, and is stronger during the hottest months and days, in vulnerable populations, and the warmest regions.” (Abstract) Chevance G, Minor K, Vielma C, Campi E, O'Callaghan-Gordo C, Basagaña X, Ballester J, Bernard P. 2024. Sleep Medicine Reviews. A systematic review of ambient heat and sleep in a warming climate. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine

Practical note

Graded very low: a single small controlled exposure study (16 participants over 65) with no replication found; downgraded for imprecision and indirectness to other age groups.

Sources

• Supports“Improving the ventilation increased the duration of deep sleep and REM sleep by 10.3 min and 3.7 min, respectively.” (Abstract) Yan Y, Zhang H, Kang M, Lan L, Wang Z, Lin Y. 2022. Indoor Air. Experimental study of the negative effects of raised bedroom temperature and reduced ventilation on the sleep quality of elderly subjects. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine
• Context“The benefits of improved thermal environment and ventilation on sleep quality were found to be additive.” (Abstract) Yan Y, Zhang H, Kang M, Lan L, Wang Z, Lin Y. 2022. Indoor Air. Experimental study of the negative effects of raised bedroom temperature and reduced ventilation on the sleep quality of elderly subjects. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine

Practical note

Graded very low: one observational study of 46 children followed for one week; downgraded for imprecision and the interpretational caveats the authors note on the income pathway.

Sources

• Supports“We found consistent evidence for a curvilinear association between NBT and sleep variables at the between-person level, indicating that children who slept in rooms that were "too hot" or "too cold" experienced poorer sleep.” (Abstract) Hinnant B, Buckhalt JA, Brigham EF, Gillis BT, El-Sheikh M. 2023. Journal of Applied Developmental Psychology. Socioeconomic Disparities, Nighttime Bedroom Temperature, and Children's Sleep. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine
• Context“Moreover, children in lower income-to-needs families had more extreme NBTs.” (Abstract) Hinnant B, Buckhalt JA, Brigham EF, Gillis BT, El-Sheikh M. 2023. Journal of Applied Developmental Psychology. Socioeconomic Disparities, Nighttime Bedroom Temperature, and Children's Sleep. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine

Practical note

Graded very low: drawn from a narrative review of small laboratory studies; the review authors call for further research on cold exposure.

Sources

• Supports“On the other hand, cold exposure does not affect sleep stages, though the use of beddings and clothing during sleep is critical in supporting thermoregulation and sleep in cold exposure.” (Abstract) Okamoto-Mizuno K, Mizuno K. 2012. Journal of Physiological Anthropology. Effects of thermal environment on sleep and circadian rhythm. CC BY; credit Okamoto-Mizuno and Mizuno, Journal of Physiological Anthropology 2012; Courtesy of the U.S. National Library of Medicine
• Context“However, cold exposure affects cardiac autonomic response during sleep without affecting sleep stages and subjective sensations.” (Abstract) Okamoto-Mizuno K, Mizuno K. 2012. Journal of Physiological Anthropology. Effects of thermal environment on sleep and circadian rhythm. CC BY; credit Okamoto-Mizuno and Mizuno, Journal of Physiological Anthropology 2012; Courtesy of the U.S. National Library of Medicine

Practical note

Graded low: a professional policy statement whose underlying evidence on overheating is observational; the policy grades each recommendation in its full text, which was not reviewed here.

Sources

• Supports“The American Academy of Pediatrics recommends a safe sleep environment to reduce the risk of all sleep-related deaths. This includes supine positioning; use of a firm, noninclined sleep surface; room sharing without bed sharing; and avoidance of soft bedding and overheating.” (Abstract) Moon RY, Carlin RF, Hand I; Task Force on Sudden Infant Death Syndrome and the Committee on Fetus and Newborn. 2022. Pediatrics. Sleep-Related Infant Deaths: Updated 2022 Recommendations for Reducing Infant Deaths in the Sleep Environment. publisher copyright; metadata and short quotes only; Courtesy of the U.S. National Library of Medicine