We’ve all experienced them: Those sweaty, miserably humid summer nights when it’s just too hot to sleep. But why does the weather have such an impact on our snooze time?
“The brain regulates body temperature and sleep in a shared area called the hypothalamus, so it’s not surprising that there’s a relationship,” says neurologist and sleep expert Brian Murray. “The body regulates temperature carefully within a few degrees, and a slight drop in body temperature facilitates sleep onset. This is the basis of the traditional suggestion of a warm bath before bedtime — it’s the slight cooling off after the bath that helps,” he explains. “People will fall asleep easier in a slightly cool, but comfortable, room temperature.”
That also means the opposite holds true, too. That is, if you’re distressingly hot — as you would be without the blessed gift of air conditioning in hellishly high temperatures — sleep becomes elusive, and humidity doesn’t help matters. “Humidity interferes with the sweating response that cools the body, so there’s more difficulty in inducing that drop in body temperature,” Murray explains.
So how can you stay cool at night during a heat wave? First, choose sheets in breathable fabrics made from natural fibers like cotton, linen or silk. Don’t touch polyester with a 10-foot pole, and for the love of Hypnos (that’s the Greek god of sleep, casuals) stay away from “cozy” weaves like flannel. Sticking your sheets in the freezer before bedtime also will help keep your body cooler, but make sure they stay dry: Like the humidity in the air, “Damp sheets might interfere with the loss of skin sweat and hinder the body’s cooling response,” warns Murray.
Ditching all blankets is a no-brainer, but if you’re the kind of person who can’t fall asleep without the comforting weight of some sort of covering, opt for your lightest top sheet, or switch out your heavy winter duvet for a summerweight version. Look for one with a low TOG (Thermal Overall Grade rating); anything 4.5 or lower will work for the summer months.
When it comes to the great Naked vs. PJs debate, the jury’s still out. Some people believe sleeping in the nude means that sweat stays on the body rather than being wicked away by fabric, while others think the less clothes, the better. “Sleep however you feel comfortable and is socially acceptable!” says Murray diplomatically, adding that sleeping on your side is a good idea, since it “increases your body’s surface area exposure to air and should lead to more cooling.” And though you’re already on your side, just say no to clammy spooning.
Because heat rises, you might want to consider sleeping in your basement as well if that’s an option. Either way, don’t underestimate the power of an electric fan or three: You could spend next to nothing on a no-frills model, or blow a thousand bucks on a fancy designer version, but a decent mid-range pedestal or tower fan will make a world of difference in your bedroom — aim that sucker right at your face for maximum cooling effects.
Finally, while it might seem tempting to grab a pillow and sleep outside under the stars, Murray doesn’t recommend it. “A raccoon bite will be a lot more of a problem than a bit of sleep disruption,” he says.
So that settles that, I guess.