Does hydration affect your sleep?
You've probably heard the advice to stop drinking water before bed. And you've probably also woken at 3am with a dry mouth and a pounding head. Both are hydration and sleep problems, just from opposite ends.
Short sleep can leave you dehydrated
While you sleep, your body releases a hormone called vasopressin, which tells your kidneys to hold onto water. It's a big reason you can go hours without a drink or a bathroom trip.
Researchers think a good chunk of that release happens later in the night, which may be why cutting sleep short seems to leave people less hydrated. A large study of adults found that people sleeping around six hours were more likely to be under-hydrated than people getting eight. So a rough night can set you up for a dry, sluggish day before you've even had breakfast.
And being under-hydrated can make sleep worse
It works the other way too. A dry mouth and throat can wake you, and going to bed low on fluids can leave you feeling groggy and headachey in the morning. The research here is still developing, so it's best thought of as one piece of the puzzle rather than a cure-all. But it's an easy piece to fix.
Drinking too much, too late, has its own cost
Down a big glass of water right before bed and you'll probably be up for the bathroom at 2am, which fragments your sleep just as badly. The goal is to be well hydrated by bedtime, not to catch up at the last minute.
A FEW THINGS WORTH TRYING
Taper off in the evening. Drink most of your water earlier in the day, then ease off in the last hour or two before bed.
Keep your electrolytes to the daytime. If you use electrolytes, have them earlier in the day or with your evening meal rather than right before bed, so you're not trading hydration for bathroom trips.
Go easy on alcohol at night. It's dehydrating and tends to break up your sleep, which is why a big night out rarely means a good night's sleep.
Keep a small glass by the bed. Then a dry mouth at 3am doesn't mean a trip to the kitchen and a fully awake brain.
Watch the room. Very dry, hot air can dry out your nose and throat overnight, so a slightly cooler bedroom often helps.
If you're waking several times a night to urinate, are constantly thirsty, or you snore loudly and wake gasping, mention it to your doctor. Those can point to something other than hydration.
You can't drink your way to perfect sleep. But being properly hydrated earlier in the day takes one common sleep disrupter off the table.