When winter comes, southern Californians don't always handle the cold well. For people who live where it's generally 'sunny and 75,' anything below 60 degrees feels like an arctic freeze, which means thermostats get cranked up until the sun returns.
While it's tempting to keep your home snuggly warm at 70 degrees or more, heat isn't ideal for sleep. Researchers have found that people who experience overheated sleep often have elevated cortisol levels (stress hormone) the following morning. Studies also show that people who sleep in warmer temps often don't sleep as well or as long. Ultimately, poor sleep or lack of sleep (sleep deprivation) causes higher blood sugar levels, increases triglycerides (fat levels), and slower metabolism.
By contrast, people who sleep in cool to cold environments tend to sleep well. A study of people with sleep disorders found that they slept longer in temperatures of 61 degrees versus those who slept in 75 degrees. The study also found that people who slept in cooler temperatures were also more alert the next morning.
It's basic physiology at work. Our body's heart rate, blood sugar, and core brain / body temperature all decrease as we prepare to sleep. When you attempt to sleep in an overly warm room, you interfere with this process and your body is not able to regulate a core temperature that induces and prolongs sleep, so you sleep badly and wake up more often.
Experts suggest that you keep your thermostat between 61 and 67 degrees. Chris Winter, MD, president of Charlottesville Neurology and Sleep Medicine in Virginia, told Health that he thinks 65 degrees is ideal. "That doesn't mean 66 or 67 is terrible, but a cooler environment usually lends itself to a better quality of sleep."
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