What Is The Optimal Temperature For Sleep?

There's not an easy answer here, but here are some tips for finding *your* optimal temperature

If you do a little research on sleep temperature, you’ll find that experts generally recommend a room temperature of 66-70 degrees as being optimal for sleep.

This is a generalization of course, but it tends to be close to the mark for most people.

On the other hand, if you have serious trouble sleeping, you’ve probably found that simply setting your thermostat for 68 doesn’t solve the problem.  Or maybe sometimes it seems to, and other times it doesn’t.

Of course at this point you should also be asking– shouldn’t it depend on the temperature during the day?  After all, people in the tropics don’t all have insomnia.  

What the research suggests is that this 66-70 degree range is a good starting point, but there’s a lot more going on with sleep temperatures.

There’s An Optimal Temperature, But It’s Not Set In Stone

Body temperature is indeed a major regulator of sleep, and as logic would dictate, your body should be significantly cooler at night than during the day.  In fact, higher temperatures are associated with more sleep disruption on a population level– another finding that probably won’t surprise anyone who’s experienced a heat wave.  

On the other hand, insomniacs, especially older ones, may actually sleep better if their skin is warmed up by .4 degrees Celsius, or .7 degrees Fahrenheit.  Curiously, this skin warming does not increase core body temperature, as the body seemingly slows its metabolism to compensate.  This suggests that insomniacs may have trouble sensing the optimal sleep temperature and adjusting their sleep environment accordingly.   

It is, of course, also true that you have to take personal comfort into account.  Any temperature that feels uncomfortable is automatically going to be a problem. Another thing that you might try is finding a temperature just one or two degrees higher than the point at which you start shivering.

Although not tested, it is very likely true that the optimal temperature for sleep is actually relative to the temperature during the day.  If it was 90 degrees during the day, 72-75 might be ideal for sleep, while during cold winters, 60-64 might be more ideal. This is somewhat speculative, but it makes logical sense– people do manage to sleep in a wide variety of climates, so the human body has to have a lot of flexibility about this.

Additionally, the optimal sleep temperature may be relative not only to daytime temperature, but to the temperature just a few minutes earlier.  

Sleep Temperature: All About Timing

Quite a few studies now suggest that what matters is not merely your body temperature when you sleep, but the rate of change. 

Taking a warm bath or shower before bed can greatly shorten sleep onset times and help you get into a deeper sleep, earlier in the night.  It seems to be not the bath itself, but the rapid cooling afterward which causes this.

Further studies suggest that sleep may be related not merely to ambient temperature, but to a variety of thermoregulatory behaviors which serve to adjust core body temperature.  Sleep is associated with a lower core body temperature, regardless of ambient temperature– but sometimes this actually correlates with increased skin temperature as the body sheds heat more effectively.  

In fact, one study found that non-REM onset is most likely when core body temperature is declining the fastest.  It is the rate of decline, more so than the absolute temperature, that seems to matter.

What all of this suggests is that you should aim for 66 degrees during sleep onset, in line with common wisdom– but more importantly, you should try to rapidly plummet your body temperature shortly before bed, rather than gradually cooling down.

You can do this by taking a warm shower before bed and allowing yourself to be cold as you dry off.  Alternatively, you might set your air conditioner to run at full blast until shortly after bedtime, then turn down or off.  Finally, you could simply open your windows on a cold night, only to close them shortly before bed, replacing them with a gentle fan for continued cooling.   

Bottom line: this takes some experimentation and I can’t give you an easy one-size-fits-all answer. But now you have some guidelines and things to experiment with.