Everyone wakes up a little during the night as your brain moves through its sleep cycles; usually you just roll over and don't remember it at all. But sometimes you completely wake up and are left staring down the numbers on the clock, doing the math on how long you have until it's time to get ready for work.
Just one night of interrupted sleep is enough to produce a measurable uptick in depression, confusion, and simple errors, according to an Israeli study. If that continues night after night, the disruption can have a profound effect on your body. Your hunger and stress hormones are thrown out of whack, your blood pressure spikes, your libido takes a nosedive, and even your immune system can be compromised. Lack of sleep can also lower glucose tolerance and insulin sensitivity and put you at a higher risk of heart disease. It's all enough to keep you up at night.
If you have trouble staying asleep, a few common habits may be to blame. Here's how you can adjust them and sleep like a baby once again.
You go to bed blitzed
Yes, you will fall asleep faster with a couple drinks in you but, unfortunately, alcohol in your system also makes you sleep terribly. In an Australian study of college-aged adults (the legal drinking age down under is 18), researchers found people who turned in with a blood alcohol level of 0.10 woke up during the night more often compared to when they nodded off sober.
In a follow-up study, the same researchers discovered that when you snooze under the influence, your brain produces more delta wave patterns on an electroencephalogram (EEG)—patterns that typically show up during the most restful phase of sleep. Sounds great, right? But at the same time, an alcohol-saturated brain also pushes out alpha patterns, which reflects a brain that is awake and passive, like when you close your eyes and meditate. The scientists concluded that these two competing wave patterns mean you'll roll out of bed feeling like you haven't slept at all, because as far as the restoration of your brain is concerned, you haven't.
You sat on your ass all day
Hate to break it to you, but moving your body more than just the minimum amount necessary to exist is associated with better sleep. In a small study at Appalachian State University, researchers tested whether strength training for 30 minutes at various times of the day could impact sleep patterns (the subjects used exercise machines, FYI). Overall, they found participants had fewer wake-ups if they had worked out that day compared to days they didn't get after it. What's more, people who exercised around 7 pm slept the most soundly compared to hitting the gym at either 7 am or 1 pm. (But maybe don't do a super-hard workout at 10 pm: Other research suggests that high-intensity sessions close to bedtime could make it harder to fall asleep in the first place.)
The researchers believe that evening workouts are effective not only because they tire you out, but because they temporarily bump up your body temperature, thereby making you cool yourself off, a process known as temperature downregulation. We tend to fall asleep as our body temperature starts dropping at night, and cooling down post-workout could augment this natural shift—it's the same idea as taking a warm bath or drinking herbal tea before bed. Which brings us to the next point.
Your bedroom is too hot
Normal body temperature is 98.6 degrees, but as part of your circadian rhythm, that reading can drop a couple degrees during the hours when you're supposed to be in heavy slumber (generally around 4 am for most people). Sleeping in a room that's too hot—or even with a blanket that's too heavy—makes your body work harder to cool down, which keeps you from hitting that restful phase of sleep, according to a Japanese review of sleep studies. Hot, humid environments are even worse: They prevent your sweat from evaporating to cool you off enough to let your body drop. Being too cold will also wake you up, but generally a blanket will keep you warm enough if you're indoors, the researchers note.
You don't have a noise strategy
The world doesn't care that you're trying to rest. During the night, your furnace flips on and off, radiators clank, neighbors slam car doors, and dogs bark. Noises as soft as 33 decibels—quieter than a library or a bird call—can raise alertness levels in your brain while you sleep and trigger muscle movements, meaning that, at best, you'll spend less time in the most restful phase of sleep and wake up groggy. But since it's the sudden, louder sounds that wake you up, you can mask them with something called pink noise, a more balanced form of white noise. When researchers in China played pink noise while 40 people slept, they found it increased their stable sleep time compared to no noise at all. Other studies have found that if the pink noise is tuned to your brain patterns (seriously) you'll wake up with better recall of the stuff you learned yesterday. You can't pull that off at home, of course, but you can find hours of soothing pink noise on YouTube, buy a pink noise machine, or simply turn on a small fan.
You're addicted to Instagram
Experts have been warning us for what seems like an eternity now that the blue light from our phones, tablets, and computers is screwing up our slumber. (In essence, short wavelength light from our gadgets mimics daylight and suppresses the production of melatonin, a hormone that helps you sleep.) Harvard researchers had a dozen people use either a backlit e-reader or read a real book before bed for five consecutive nights in a 2015 study. The e-reader group took an average of 10 minutes longer to fall asleep than the analog folks; they also woke up feeling groggier and it took them several hours longer to reach the same self-reported levels of alertness.
Most devices now come with a "night mode" to reduce that blue light, but even the kinds of things you're looking at during the day could be linked to your crappy sleep. In one study, people ages 19 to 32 who spent more than two hours a day on social media were nearly twice as likely to report sleep disturbances as people who were on Facebook and Twitter less for than 30 minutes. Even people in the second-lowest quartile of social media use, between 30 and 60 minutes a day, were 26 percent more likely to wake up at night. If you want to cut back, you can try turning off notifications or deleting the apps from your phone so you're forced to open a browser tab.