Hot Summer Nights
- Jaime K. Devine, PhD
- 6 days ago
- 5 min read
Do you have a favorite song about hot summer nights? I enjoy “Summer Lovin’” from the musical Grease and “Heat Waves” by Glass Animals but nothing beats the lyrics in Jason Derulo’s song “Want to Want Me” for the purposes of today’s blog post. “Want to Want Me” concisely summarizes the impact of high ambient temperature on sleep quality with the opening lyrics:
“It’s too hard to sleep.
I got the sheets on the floor, nothing on me.
And I can’t take it no more, it’s a hundred degrees.”
You can find the music video for “Want to Want Me” on YouTube, but I don’t recommend watching it in the office. It may result in an awkward conversation with your coworker about how you’re only watching a video that heavily features a scantily-clad woman writhing on an unmade bed as research for a blog post about the impact of high ambient temperatures on sleep quality.
Pop culture and awkward office encounters aside, temperature is an underappreciated environmental factor that influences sleep. Bedrooms that are either too hot or too cold result in shorter sleep time and altered sleep architecture in humans [1]. Exposure to cold temperatures is worse for sleep than heat, but also more easily mitigated by warm blankets and snuggly pajamas. Ambient heat is harder to avoid. Heat exposure increases wakefulness and decreases time spent in deeper sleep stages like slow wave sleep (SWS) and rapid eye movement (REM) sleep [1]. This is not a new finding. One of the first laboratory studies that focused on the influence of temperature on sleep used an electric blanket that amped all the way up to 49°C (120°F) to heat up ten healthy male volunteers back in 1978 [2]. The 1978 laboratory study stated that average nighttime temperatures greater than 24°C (~75°F) were already known to disrupt sleep duration prior to their investigation.
The impact of heat on sleep has not changed in the last half century, but the number of hot nights has. A 2026 study published in Nature found that global temperatures, including the number of nights when temperatures did not drop below 20°C (68°F) have risen markedly since the 1970s [3]. Globally, we’ve gained two additional hot nights per year. That may not seem like a lot, but the study also pointed out that regions that previously did not experience extreme heat are now affected. Parts of North America and Europe, Africa, and South America all now experience up to 50 more heat stress days per year than they did historically [3].
Relatedly, a 2025 study analyzed longitudinal data collected by the All of Us Program between 2010 and 2022 to assess relationships between temperature and sleep. The analysis focused on individuals who provided sleep data through Fitbit devices for at least three months and who provided location data in the form of their home zip code. The researchers used meteorological data and zip codes to estimate daily temperatures. The authors then calculated the difference between daytime and nighttime minimum temperatures for each day in the 2010-2022 dataset relative to the long-term average daily minimum temperature for that day based on data from 1990–2009. They hypothesized that higher nighttime temperatures relative to the historic average would be related to poorer sleep measures. The final analysis included over 12 million datapoints collected from over 14,000 participants. As the authors hypothesized and Jason Derulo’s lyrics suggest, hot nights (those that were 10°C higher than the historic average) were associated with decreased sleep efficiency, increased awakenings, increased time to sleep onset, and reduced time spent in REM, light, and deep sleep stages. Daytime temperatures exceeding 10°C of the historic average were also associated with sleep disturbances.
So, what can we do to protect sleep quality during hot nights? “Fight climate change” is the obvious answer, but slightly out of scope for the individual sleeper. Cranking the air conditioner (AC) is a quick fix for those of us with access to temperature-controlled environments. However, air conditioning is not as ubiquitous as it seems. Not only is there an economic consideration for the installation and cost of running the AC, but it has regional popularity as well. A colleague in Europe was recently complaining about the heat wave (read here); she pointed out that most homes in her country do not have air conditioning because historically, they didn’t need it. Another problem with air conditioning is that the sound of the unit kicking on in the middle of the night is really annoying. This is not just my personal opinion; there is actually laboratory data supporting the negative impact of AC noise on sleep quality and mood [4].
A 2024 Nature study tested passive or low-energy solutions for temperature extremes during sleep using thermal manikin [5]. The paper recommends using a fan or a temperature-controlled mattress to reduce temperatures. Sleepers can also ditch their pajamas, sleep on the floor or a hammock instead of a mattress and spread out their limbs to sleep in a starfish position if they are hot. The study also tested strategies for cold weather as well. For convenience, an adaptation of Figure 6 from the 2024 Nature paper has been reproduced below with mitigations for heat highlighted in red.
Many of the strategies in the figure above can also be observed in the “Want to Want Me” music video. Derulo is shown in the starfish position on a bed with a pedestal fan blowing in his direction. He is not wearing any pajamas. His female counterpart in the video, portrayed by actress Tianna Gregory, engages in similar tactics to reduce her ambient temperature. Unfortunately, the mitigation strategies don’t work, so they are forced to get out of bed and perform choreography for the rest of the video. Hopefully you’ll have better luck than Jason Derulo cooling down enough on a hot night to get good quality sleep.
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