What is the best temperature for sleeping? About 66 to 70°F (19 to 21°C) for most adults, per a 2019 sleep physiology review, and 68 to 77°F for adults over 65, per a 2023 in-home study. A bedroom that runs too warm costs more sleep than one that runs slightly cool.
Key Takeaways
- Across 10,903 person-nights in Boston homes, adults 65+ slept best at 20 to 25°C (68 to 77°F), per Baniassadi et al., 2023.
- The same study predicted a 60-minute loss of total sleep as bedrooms warmed from 22 to 30°C (about 72°F to 86°F).
- Adults over 65 slept 26.3 minutes less at 30°C than at 27°C, even with a ceiling fan on, per Yan et al., 2022.
- Under bedding, sleep stages did not differ across 13 to 23°C (about 55 to 73°F), per a 2012 review.
- The American Academy of Pediatrics gives no room temperature for babies; it says dress them in one layer more than you wear.
- The WHO housing guidelines (2018) set an 18°C (about 64°F) cold-season minimum, higher for some older people.
What is the best temperature for sleeping?
The best temperature for sleeping is a band: roughly 66 to 70°F (19 to 21°C) for healthy adults and 68 to 77°F (20 to 25°C) for adults over 65. Below it, sleep holds up under blankets. Above it, sleep gets shorter and more broken.
The popular 60 to 67°F range is not wrong, but the top-ranking pages we checked attribute it to experts, not to a study that tested it. Here is the research itself.
| Study | Who slept, where | Conditions | Finding |
|---|---|---|---|
| Baniassadi et al., Science of the Total Environment, 2023 | 50 adults aged 65+, own homes, Boston | Home sensors, 10,903 person-nights | Most efficient, restful sleep at 20 to 25°C (68 to 77°F) |
| Yan et al., Indoor Air, 2022 | 16 adults over 65, lab bedrooms, Shanghai | 27°C vs 30°C, ceiling fan on at 30°C | At 30°C: 26.3 minutes less sleep, efficiency down 5.5% |
| Okamoto-Mizuno and Mizuno, J Physiol Anthropol, 2012 | Review of lab studies | Semi-nude vs with bedding | No sleep stage difference from 13 to 23°C with bedding; heat disturbs more than cold |
| Harding, Franks and Wisden, Frontiers in Neuroscience, 2019 | Review | Room vs skin temperature | Optimal room about 19 to 21°C; skin microclimate 31 to 35°C |
| Haghayegh et al., Sleep Medicine Reviews, 2019 | Meta-analysis, 17 studies | Warm bath or shower before bed | 40 to 42.5°C water, 1 to 2 hours before bed, faster sleep onset |
| WHO Housing and Health Guidelines, 2018 | General population | Cold-season minimum | 18°C; higher may be needed for older people and children |
Why does a cooler bedroom help you fall asleep?
A cooler bedroom helps because the body dumps heat to fall asleep. Blood vessels in the hands and feet open and core temperature falls. A warm room slows that heat loss, so the drop that signals sleep arrives late.
A 2019 review in Frontiers in Neuroscience notes this widening of vessels can start up to 2 hours before sleep. It puts optimal room temperatures at approximately 19 to 21°C, with the skin microclimate at 31 to 35°C.
That explains a backwards-sounding result. A 2019 meta-analysis of 17 studies found that a warm bath or shower of 40 to 42.5°C (about 104 to 108°F), taken 1 to 2 hours before bed for as little as 10 minutes, shortened the time it took to fall asleep. The heat pushes blood to the palms and soles, so the body then cools faster.
Is heat or cold worse for sleep?
Heat is worse in a real bedroom. Without covers, the reference point is a thermoneutral 29°C (about 84°F), and air warmer or cooler than that adds wakefulness. Once bedding and nightclothes are added, cold stops affecting sleep stages, while heat still increases wakefulness and cuts slow wave and REM sleep.
That is the conclusion of the Okamoto-Mizuno and Mizuno review, which notes that studies with bedding found no significant sleep difference from 13 to 23°C. The covers do the work: normal sleep coincides with a bed climate of 32 to 34°C and 40 to 60% relative humidity.
The Boston home data show the same lopsided curve. Warming the bedroom from 22 to 30°C went with a 10% drop in sleep efficiency; cooling it from 22 to 14°C (about 57°F) went with a 5% drop. Total sleep time did not change until the room passed 22°C.
Correction
Colder is not always better. The 2012 review found cold changed the heart’s autonomic response during sleep even when sleep stages looked normal, and it says winter room temperature should stay above 10°C (50°F). Also check conversions on sleep pages: 15.6°C is 60°F, not 65°F, and 65°F is 18.3°C.
Is the best temperature for sleeping different after 65?
Yes. Older adults sleep best in a warmer band, 68 to 77°F (20 to 25°C) in the strongest home data, and heat costs them more.
The Baniassadi study followed adults 65 and older in their own homes from October 2021 to February 2023, pairing bedroom sensors with a sleep-tracking ring. Temperature was significantly linked to total sleep time in 29 of 45 participants, but the direction varied, so the authors call for personalized settings.
Lab data agree. In the Yan study, 30°C cut sleep efficiency by 5.5% versus 27°C, and the 2012 review says mild heat doubled whole-body sweat loss in elderly sleepers. Heat at night is also a safety issue, covered in our review of heat deaths and air conditioning access.
Cold has a floor too. WHO calls 18°C a widely accepted minimum and says older people, children and the chronically ill may need it higher.
What humidity is best for sleeping?
About 50% relative humidity. In the Boston study, sleep efficiency followed an inverse U against bedroom humidity, peaking at 50%, though humidity mattered less than temperature over the range observed. Under the covers, normal sleep coincides with 40 to 60% relative humidity.
Humidity matters most in heat: humid air stops sweat evaporating, so heat builds, per the 2012 review. In one experiment, 32°C at 80% relative humidity affected slow wave sleep but not REM. For whole-house targets by season, see our guide to indoor humidity levels. In a muggy climate, a properly sized dehumidifier can pull a bedroom back toward 50%.
Best temperature for sleeping with a baby: what do AAP and NIH say?
Neither gives a number. The American Academy of Pediatrics says overheating can increase the risk of SIDS and a baby needs only one more layer than an adult in the same room. The warmer baby-room ranges quoted on sleep sites come from individual experts, not from AAP guidance.
The NIH Safe to Sleep campaign says overheated babies are at higher risk for SIDS and heat-related death. Between them, the two give these checks:
- Watch for sweating, flushed or hot skin, or a hot chest.
- Take the baby’s hat off once indoors.
- Use a wearable blanket or one extra clothing layer, not loose blankets.
- Dress the baby for the temperature of the room.
How should you set the thermostat for the best sleep temperature?
Keep the bedroom itself inside the evidence band and let bedding handle the cold:
- Measure at the bed; the thermostat may sit in another room.
- Start near 68°F (20°C), where the adult and over-65 bands overlap, then adjust one degree at a time.
- Schedule the night setting 1 to 2 hours before bedtime, matching the window when the body starts shedding heat.
- In summer, keep the bedroom at or below 77°F (25°C); sleep efficiency fell above that in the Boston data.
- In winter, add blankets before turning up the heat, and stay above 64°F (18°C) for older sleepers.
A smart thermostat automates step 3. Setback savings are in our thermostat settings guide; DOE’s Energy Saver page (archived copy) says turning back 7 to 10°F for 8 hours a day can save as much as 10% a year on heating and cooling.
The trade-off is summer. DOE advises setting the cooling thermostat as high as is comfortable when you are home, but a bedroom that drifts past 77°F works against the sleep data. Compare your setting with what Americans actually set, and see our review of workplace temperature research for daytime comfort.
Fans do not replace cooler air: the Yan study ran a ceiling fan at 30°C and sleep still suffered. Set the ceiling fan direction for summer, check that equipment noise stays low using our AC decibel ratings explainer.
In winter, an electric blanket warms the bed rather than the house.
How we researched this
Research date: October 31, 2026. After reviewing the top-ranking pages, we read three full-text papers on PubMed Central, two PubMed abstracts, the WHO guidelines PDF, AAP and NIH safe sleep pages and an archived DOE page. All nine are cited.
Fahrenheit values are our conversions. Excluded: mattress and app company claims, an industry-funded heated-mattress trial, expert-quote ranges with no study behind them, and Reddit (health topic). The thermostat steps are our synthesis, not a clinical guideline.
Frequently asked questions
Is 65 degrees too cold to sleep?
Not for most adults under normal bedding. A 2012 review found no significant sleep stage differences between 13 and 23°C (about 55 to 73°F) with bedding and nightclothes. 65°F is about 18.3°C, just above the WHO minimum of 18°C. Older adults may sleep better warmer.
Is 75 degrees too hot to sleep?
For adults over 65 it is inside the 20 to 25°C (68 to 77°F) best range from the 2023 Boston study. For younger adults it sits above the 19 to 21°C optimum in a 2019 review. In the Boston data, total sleep time started falling once bedrooms passed 22°C, about 72°F.
What temperature should a baby’s room be at night?
Neither the AAP nor the NIH Safe to Sleep campaign gives a number. The AAP says to dress a baby in one layer more than an adult would wear in the same room, skip hats indoors, and check for sweating, a hot chest or flushed skin, because overheating can increase SIDS risk.
Does humidity affect sleep?
Yes, mainly in warm rooms. In the 2023 Boston study of older adults, sleep efficiency peaked at about 50% relative humidity. A 2012 review found humid heat adds thermal load because sweat cannot evaporate, and normal sleep coincides with 40 to 60% humidity under the covers.
Why do I sleep badly in a hot bedroom?
Heat blocks the core temperature drop that sleep depends on. In a 2022 lab study, adults over 65 at 30°C slept 26.3 minutes less and spent 27.0 more minutes awake than at 27°C, even with a ceiling fan running. A 2012 review found heat cuts slow wave and REM sleep.
Does a warm shower before bed help you sleep?
It can. A 2019 meta-analysis of 17 studies found water at 40 to 42.5°C, used 1 to 2 hours before bedtime for as little as 10 minutes, shortened the time to fall asleep, by sending blood to the hands and feet.
Sources
- Baniassadi A et al., Science of the Total Environment. “Nighttime ambient temperature and sleep in community-dwelling older adults (2023).” https://pmc.ncbi.nlm.nih.gov/articles/PMC10529213/. Accessed October 2026.
- Yan Y et al., Indoor Air. “Negative effects of raised bedroom temperature and reduced ventilation on sleep quality of elderly subjects (2022).” https://pubmed.ncbi.nlm.nih.gov/36437666/. Accessed October 2026.
- Okamoto-Mizuno K, Mizuno K., Journal of Physiological Anthropology. “Effects of thermal environment on sleep and circadian rhythm (2012).” https://pmc.ncbi.nlm.nih.gov/articles/PMC3427038/. Accessed October 2026.
- Harding EC, Franks NP, Wisden W., Frontiers in Neuroscience. “The Temperature Dependence of Sleep (2019).” https://pmc.ncbi.nlm.nih.gov/articles/PMC6491889/. Accessed October 2026.
- Haghayegh S et al., Sleep Medicine Reviews. “Before-bedtime passive body heating by warm shower or bath to improve sleep (2019).” https://pubmed.ncbi.nlm.nih.gov/31102877/. Accessed October 2026.
- World Health Organization. “WHO Housing and Health Guidelines (2018).” https://iris.who.int/server/api/core/bitstreams/be014865-921a-482c-89e4-9191c7476e13/content. Accessed October 2026.
- American Academy of Pediatrics, HealthyChildren.org. “A Parent’s Guide to Safe Sleep.” https://www.healthychildren.org/English/ages-stages/baby/sleep/Pages/a-parents-guide-to-safe-sleep.aspx. Accessed October 2026.
- NIH NICHD, Safe to Sleep. “Ways to Reduce Baby’s Risk.” https://safetosleep.nichd.nih.gov/reduce-risk/reduce. Accessed October 2026.
- US Department of Energy, Energy Saver. “Programmable Thermostats (archived copy).” https://web.archive.org/web/2025id_/https://www.energy.gov/energysaver/programmable-thermostats. Accessed October 2026.
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