Under the Covers: The Effect of a Temperature-Controlled Mattress Cover on Sleep and Perceptual Measures in Healthy Adults
Study by S. Stevenson, H. Suppiah, T. Mündel and M. Driller
Randomised Crossover Study · Clocks & Sleep (Vol. 7, Issue 4, Article 55) · DOI: 10.3390/clockssleep7040055
Key Takeaway
A Cooling Mattress Cover Made People Feel They Slept Better, but Measured Sleep Did Not Change
What was tested: 34 healthy adults used a temperature-controlled mattress cover at home for 14 nights: 7 with the temperature feature on and 7 with it off, in random order (Stevenson et al., 2025).
What the numbers showed: With the feature on, people rated their sleep quality and thermal comfort better on every daily measure. Wrist trackers and sensors in the cover found no significant change in sleep, heart rate, heart rate variability or breathing rate.
What this means for you: A cooling cover may help you feel more comfortable in bed. The authors say the better ratings may partly reflect expectation or placebo effects, since measured sleep did not change.
Key Numbers
How the Study Was Done
In a randomised, counterbalanced crossover study, 34 healthy adults (20 women and 14 men, average age 30) first used a temperature-controlled mattress cover for at least 3 nights to get used to it. They then used it for 14 nights: 7 with the temperature feature on and 7 with it off (Stevenson et al., 2025).
Sleep was measured with a wrist activity tracker (actigraphy). Heart rate, heart rate variability and breathing rate were recorded by sensors built into the cover. People also filled in daily and weekly questionnaires on sleep quality, thermal comfort and how warm or cool they felt.
What the Study Compared
Temperature Feature On (7 Nights)
Better self-rated sleep quality and thermal comfort on all daily measures.
Temperature Feature Off (7 Nights)
The comparison week on the same cover. Measured sleep and heart and breathing data were not significantly different.
What the Study Found
The daily questionnaires favoured the nights with the temperature feature on for every perceived outcome, including sleep quality and thermal comfort. There were no significant differences in the objective sleep measures or the heart and breathing data (Stevenson et al., 2025).
The authors say the improvement in how people felt, without changes in measured sleep, may in part reflect expectancy or placebo effects. They call for longer studies. The research was funded by an internal La Trobe University grant, and the authors declare no conflicts of interest.
In an earlier lab study in a hot room (32°C), cooling the back and head raised average sleep efficiency from 84.6% with no cooling to 95.3%, and cooling the back alone raised it to 92.8% in 16 men (Lan et al., 2018). An earlier version of this page cited a 2017 study whose DOI belongs to an unrelated paper; we could not find it, so its figures have been removed.
How to Apply This Study When Choosing a Mattress
What it tells you: Cooling can make bed feel more comfortable, especially in a hot room.
In a normal-temperature bedroom, a cooling cover may change how you feel more than how you sleep. Use the return window to judge it for yourself.
Study Scope and Limitations
34 healthy adults, 7 nights per condition, and sleep measured with a wrist tracker rather than a sleep lab. The temperature under the covers and body temperatures were not measured. Only one cover design was tested.
Primary Citation
Stevenson, S., Suppiah, H., Mündel, T., & Driller, M. (2025). Under the covers: The effect of a temperature-controlled mattress cover on sleep and perceptual measures in healthy adults. Clocks & Sleep, 7(4), 55. https://doi.org/10.3390/clockssleep7040055