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Most people are aware of the basic do’s and don’t before bedtime that affect sleep: Do things that are relaxing like taking a warm shower, pleasure reading, listening to music, stretching, or meditating; don’t do things that are stress inducing like exercising strenuously, eating or drinking caffeine, working, thinking or talking about stressful topics.

What is not widely known, and strange as this may sound, the temperature of your skin is critical to being able to fall asleep quickly and stay asleep through the night. Here is what happens and how skin temperature affects your sleep.

• An hour or two before your typical bedtime, the skin of your hands, arms, legs and feet should start getting significantly warmer due to increased blood flow. 
• With this increase in skin blood flow and warmth, body heat is given off to the air surrounding the skin, causing your core body temperature to decrease gradually through the night.
• The increase in skin temperature, along with the parallel night time increase in melatonin, is what causes drowsiness and the rapid onset of sleep when you turn out the lights.
• When skin blood flow and warming cannot increase due to vasoconstriction (narrowing of the blood vessels), getting to sleep will take longer, staying asleep can be difficult, and how much restorative slow wave sleep and learning-dependent REM sleep you get can be decreased. 

Some things that can cause your blood vessels to narrow when they should be dilating for sleep include high adrenaline levels due to stress, low blood pressure due to dehydration, a medical condition called vasospastic disorder, and a low core body temperature due to eating something very cold like ice cream.

So, here are simple things I do to help my sleep-related skin warming and improve my sleep.

• If my feet or legs are cool or cold at bedtime, I wear socks to bed and/or take a warm shower.
• I drink plenty of non-caffeinated beverages during the day and early evening so I am well hydrated by dinner time.
• When I’ve had a stressful day or feel wound up in the evening, I try to get moderate exercise in the late afternoon or early evening. I use the stress reducing activities described above to help decrease night time stress too.
• I avoid drinking and eating things that are very cold in the hour before bedtime.
• I keep the temperature of my bedroom and my bed cool enough that my skin can give off heat, but warm enough that I don’t feel chilled.

If you are familiar with the impact of skin temperature on sleep and have any tips or comments to share, your contribution to exploring this topic is greatly appreciated.

How and when your core body temperature cools at night can also affect your sleep, but I’ll save that topic for a future post.