sleep and heat resources

Green fan with dark background. Photo by <a href="">rajat sarki</a> on <a href="">Unsplash</a>

Photo by rajat sarki on Unsplash


McMillan, Matt. “What’s the Best Temperature for Sleep?” WebMD, reviewed Feb. 28, 2024. (Accessed March 10, 2024)

If you sleep hot, you’re likely to remain in the lighter stages of sleep rather than reach a deeper, more restorative and restful stage, such as what’s called slow-wave sleep. In those light stages, it’s easier for you to wake up.”

Pacheco, Danielle and Heather Wright. “Best Temperature for Sleep.” Sleep Foundation, Nov. 8, 2023. (Accessed Jan. 29, 2024.)

Cleveland Clinic. “What’s the Best Temperature for Sleep?” Nov. 15, 2021. (Accessed March 11, 2024.)

“As a rule of thumb, sleep psychologist Michelle Drerup, PsyD says to keep your bedroom at 60 to 67° F (15 to 19° C) and to think of your bedroom as your ‘cave.’ … “On the flip side, sleeping too cold also has its downsides. It may not affect your sleep cycles as drastically as sleeping too hot, but it may lead to other health issues. “When we’re cold, our body kicks into high gear to try and get us warm again,” says Dr. Drerup. Blood vessels become constricted, breathing becomes shallow and it puts extra pressure on our cardiovascular system to get our body temperatures regulated again, she adds. “If your bedroom temperature is lower than 60° F, it’s too cold.”


Altena, Ellemarije, et al. “How to deal with sleep problems during heatwaves: practical recommendations from the European Insomnia Network.” Journal of Sleep Research 32.2 (2023): e13704. Excellent overview article.

Baniassadi, Amir, et al. “Nighttime ambient temperature and sleep in community-dwelling older adults.” Science of The Total Environment 899 (2023): 165623. [PMID: 37474050] (Abstract only.)

Our findings demonstrated that sleep was most efficient and restful when nighttime ambient temperature ranged between 20 and 25 °C [68-77ºF], with a clinically relevant 5-10 % drop in sleep efficiency when the temperature increased from 25 °C to 30 °C [77-86ºF]. The associations were primarily nonlinear, and substantial between-subject variations were observed.

Cagnacci, Angelo, et al. “Homeostatic versus circadian effects of melatonin on core body temperature in humans.” Journal of biological rhythms 12.6 (1997): 509-517. [Abstract, introduction and snippets.]

It is known that melatonin enhances heat loss, but a reduction of heat production cannot be excluded.

Chimed-Ochir, Odgerel, et al. “Perception of feeling cold in the bedroom and sleep quality.” Nagoya Journal of Medical Science 83.4 (2021): 705. [PMID: 34916715]

Fujii, Hisako, et al. “Fatigue and sleep under large summer temperature differences.” Environmental Research 138 (2015): 17-21. [Abstract, intro and snippets only.]

High air temperatures in summer increased fatigue in healthy volunteers, especially those with poor sleep patterns, depending on the use of air conditioners, accommodation status, and subject’s age.

Haghayegh, Shahab, et al. “Before-bedtime passive body heating by warm shower or bath to improve sleep: a systematic review and meta-analysis.” Sleep medicine reviews 46 (2019): 124-135. [Abstract and snippets.]

Harding, Edward C., Nicholas P. Franks, and William Wisden. “The temperature dependence of sleep.” Frontiers in neuroscience 13 (2019): 336. [PMID: 31105512]

We discuss the evidence that body cooling and sleep are more fundamentally connected and that thermoregulatory behaviours, prior to sleep, form warm microclimates that accelerate NREM directly through neuronal circuits. Paradoxically, this warmth might also induce vasodilation and body cooling. In this way, warmth seeking and nesting behaviour might enhance the circadian cycle by activating specific circuits that link NREM initiation to body cooling.

Nicol, Fergus. “Temperature and sleep.” Energy and Buildings 204 (2019): 109516.


Nicol, Fergus, et al. “The range and shape of thermal comfort and resilience.” Energy and Buildings 224 (2020): 110277.

Obradovich, Nick, et al. “Nighttime temperature and human sleep loss in a changing climate.” Science advances 3.5 (2017): e1601555.

Using data from 765,000 U.S. survey respondents from 2002 to 2011, coupled with nighttime temperature data, we show that increases in nighttime temperatures amplify self-reported nights of insufficient sleep. We observe the largest effects during the summer and among both lower-income and elderly respondents. We combine our historical estimates with climate model projections and detail the potential sleep impacts of future climatic changes.

Okamoto-Mizuno, Kazue, and Koh Mizuno. “Effects of thermal environment on sleep and circadian rhythm.” Journal of physiological anthropology 31.1 (2012): 1-9. [PMID: 22738673]

The stereotypical effects of heat or cold exposure are increased wakefulness and decreased rapid eye movement sleep and slow wave sleep. These effects of the thermal environment on sleep stages are strongly linked to thermoregulation, which affects the mechanism regulating sleep… Humid heat exposure further increases thermal load during sleep and affects sleep stages and thermoregulation… However, cold exposure affects cardiac autonomic response during sleep without affecting sleep stages and subjective sensations.

Rifkin, Daniel I., Michael W. Long, and Melissa J. Perry. “Climate change and sleep: A systematic review of the literature and conceptual framework.” Sleep medicine reviews 42 (2018): 3-9.

Using a systematic search strategy, 16 studies met the inclusion criteria. Six studies related to the effects of rising temperature, seven studies related to extreme weather events, and three studies related to floods or wildfires. Diminished total sleep times and sleep disruption were most commonly reported, especially among the most vulnerable populations including the elderly and low-income; however, the body of evidence was limited and further well-designed human studies are clearly needed.

Yan, Yan, et al. “Experimental study of the negative effects of raised bedroom temperature and reduced ventilation on the sleep quality of elderly subjects.” Indoor air 32.11 (2022): e13159. [PMID: 36437666] (Abstract only.)

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, indicating that the sleep quality of the elderly is very vulnerable to heat exposure. Even a small heat load led to an overactive sympathetic nervous system and increased wrist skin temperature, which reduced sleep quality. Improving the ventilation increased the duration of deep sleep and REM sleep by 10.3 min and 3.7 min, respectively. Higher pollutant concentrations affected the respiration and autonomous nervous systems to reduce sleep quality.

Zhang, Xiaojing, et al. “Associations of bedroom air temperature and CO2 concentration with subjective perceptions and sleep quality during transition seasons.” Indoor air 31.4 (2021): 1004-1017. [PMID: 33620120] (Abstract only.)

Zheng, Guozhong, Ke Li, and Yajing Wang. “The effects of high-temperature weather on human sleep quality and appetite.” International journal of environmental research and public health 16.2 (2019): 270. [PMID: 30669302]

Significant effects were mainly reflected in sleep duration and shallow sleep. The subjective results showed that temperature had significant effects on sleep calmness, difficulty in falling asleep, sleep satisfaction, and sleep adequateness. For appetite, the VAS results indicated that high temperatures mainly led to a reduction of appetite at lunch time.


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