There’s little that’s more frustrating than being desperate for a good night’s sleep, only to find yourself wide awake at 3 a.m. If you’re feeling stressed, you might find yourself assuming cortisol is to blame.
After all, stress causes cortisol levels to rise in the body and if this disrupts your internal body clock, it can lead to interrupted sleep. But, it's not the only cause of nighttime wake-ups.
We’ve spoken to Dr. Shelby Harris, behavioral sleep medicine specialist and psychologist with BetterSleep, who has explained that there are actually a number of ways your habits in the lead-up to bedtime might be preventing you from sleeping through the night, from what you consume to how you move.
Plus, we’ve got easy fixes for these ‘bad’ habits that should help you get an uninterrupted rest.
4 nighttime habits ruining your sleep
What we do before bedtime can significantly impact our sleep and even cause those dreaded 3 a.m. wakeups. Dr. Harris shares the nighttime habits that may be disrupting your sleep and what you can do instead to help you sleep through the night.
1. Drinking alcohol (especially late at night)
"While alcohol can make you feel sleepy initially, it can disrupt the quality of your sleep as it wears off during the night," Dr. Harris says. "This can lead to lighter, more fragmented sleep and more frequent wakeups, especially in the second half of the night.
Research has shown that this is caused by alcohol metabolizing in your body, causing "sympathetic activation, increased arousability, and sleep fragmentation" — which means waking up more often and for longer.
Plus, the effects of alcohol on sleep were found to more noticeable when it was consumed closer to bedtime. And while you may think a glass of wine or two won't hurt your sleep, one 2024 study found that even light consumption of alcohol can impact sleep health.
The fix
"If you’re drinking, try to avoid having alcohol too close to bedtime and drink water alongside it," says Dr. Harris.
Another option is to try one of these five sleep inducing non-alcoholic drinks — including TikTok favorite, the Sleepy Girl Mocktail. With ingredients including tart cherry juice (which contains melatonin) and magnesium powder (magnesium has been linked to better sleep quality), this popular mocktail is doctor-approved.
2. Eating a large or heavy meal too close to bedtime
We've all been there, a busy day pushes your evening meal later. And as the colder weather sets in, it's more likely you'll be swapping light summer dishes for heavier, richer foods.
But that combination can wreak havoc on your sleep. "Going to bed immediately after a large meal can make it harder to sleep comfortably. Digestion can contribute to discomfort or reflux, and particularly rich, spicy, or fatty foods may worsen those issues and potentially disrupt sleep," says Dr. Harris.
Aside from those issues, the activation of digestion and increase in core body temperature that come with eating a big meal can both "delay sleep onset and lead to more nighttime awakenings," clinical psychologist Dr. Leah Kaylor previously explained to us.
One study found that eating within three hours of bedtime was associated with waking up during the night, while another study reported that people who ate or drank within an hour of bedtime with more likely to wake during the night compared to those who didn't eat or drink during that timeframe.
The fix
Dr. Harris advises that, "When possible, aim to finish dinner a few hours before bed. If you're genuinely hungry later, a small, balanced snack is a better option than going to bed overly full."
Our guide to six healthy nighttime snacks to help you sleep better features nutritionist-approved foods such as cherries and almonds, as well as tips on what to skip if you want to sleep well (spoiler alert — chocolate and spicy foods are best avoided).
You might also want to consider adding a little more protein to your diet, as it contains tryptophan, an amino acid that is involved in the production of melatonin (the sleepy hormone).
3. Consuming caffeine too late in the day
Dr. Harris explains that "caffeine has a relatively long half-life, meaning some of it can remain in your system for hours after you drink it."
The half-life of caffeine around 4-6 hours, which means it takes that long for your body to metabolize half of what you've consumed. So, drinking coffee, matcha tea or even eating a bar of dark chocolate, too late in the day can mean there's still plenty of caffeine in your system come bedtime.
Plus, new research shows that "even if you can fall asleep after an afternoon coffee, caffeine can reduce sleep quality and contribute to more fragmented sleep for some people," the psychologist explains.
One meta-analysis of research into the effects of caffeine on sleep found that consuming it led to an increase of 12 minutes in time awake after sleep onset (essentially the length time you wake up at night after falling asleep initially), as well as leading to more light sleep and less deep sleep.
The fix
"Instead, you can set a personal caffeine cut off earlier in the day," Dr. Harris suggests.
The research above advised that you should stop consuming caffeine around nine hours before you intend to sleep — for example, a 1pm cut off time if you plan to go to bed at 10pm.
"If you want a warm beverage in the evening, choose something caffeine-free such as herbal tea," the sleep specialist adds. Chamomile tea is a great option, as it has been shown in studies to help improve sleep quality.
4. Exercising too close to bedtime
There's plenty of research to indicate that exercise improves sleep, but as Dr. Harris explains, "intense exercise right before bed can leave your body feeling energized when it should be winding down."
"Exercise temporarily raises your heart rate, body temperature, and alertness, which can make it harder to fall asleep and, for some people, may contribute to waking up during the night," she says.
One small study found that intense aerobic exercise in the evening led to participants experiencing sleep issues, including increasing the time it took to fall asleep and the number of nighttime awakenings.
And, a meta-analysis of research into morning vs. evening exercise found that workouts in the evening or at nighttime were associated with waking up more at night.
The fix
"If you prefer exercising at night, gentler activities like stretching, walking, or yoga may be less disruptive," advises Dr. Harris.
Certain gentle exercise might even help prevent nighttime wakeups. A review of studies found that yoga, walking and Tai Chi were among the most effective at improving sleep for those with insomnia.
Alternatively, these seven stretches to do before bed include simple poses like a forward fold and child's pose, and can help relax you by activating the parasympathetic nervous system. They shouldn't cause any sleep disruptions!
How important are healthy habits in the lead-up to bedtime?
We've explored the nighttime habits that can be disruptive for sleep, but Dr. Harris explains that "healthy habits in the hours before bedtime play an important role in helping you sleep through the night."
"Sleep depends not only on how tired you are but also on your stress levels, evening routines, and environment," she adds.
The sleep expert suggests sticking to a consistent bedtime, making sure you have a relaxing nighttime routine to allow you to wind down, and limiting activities that will stimulate your brain (think scrolling on your phone or staying up late watching TV). These are all effective ways to signal to your body that it's time to rest.
And though she notes that healthy habits can't prevent nighttime wakeups altogether, "they can support more restful, uninterrupted sleep by making it easier to fall asleep and return to sleep if you do wake up."
How to tell if it is cortisol waking you up at night
If you're not sure whether cortisol is behind your nighttime awakenings, it may be useful to understand how stress impacts cortisol in the body.
Dr. Harris explains that stress "can interfere with sleep by activating the body's stress response, which involves hormones such as cortisol and adrenaline," adding that the brain stays more alert when we're stressed, which makes it harder to maintain the deeper, restorative stages of sleep.
"Although cortisol naturally fluctuates throughout the day and is generally lower at night, ongoing stress can disrupt these patterns and contribute to nighttime awakenings," she says.
As Tom's Guide sleep editor Nicola Appleton recently discovered, cortisol naturally rises from about 3 a.m. as part of our normal circadian rhythm, but if stress has raised your cortisol levels above a typical baseline level, this increase can actually wake you up.
While Dr. Harris says "it can be difficult to determine whether stress or cortisol directly causes nighttime awakenings," she adds that there are patterns people might notice that can suggest stress is contributing to disrupted sleep.
These include waking up with racing thoughts, feeling mentally alert despite being tired, experiencing muscle tension, or noticing that your heart is beating faster than usual. The psychologist adds that "consistently waking up during particularly stressful periods, such as before a major deadline or during a difficult life event, can also be a clue."
However, she points out that waking up at night can also be caused by "uncomfortable sleep environment, alcohol, caffeine, medications, or underlying sleep conditions, so these symptoms alone do not confirm that cortisol is the cause."
Here are Dr. Harris' tips for helping to prevent stress — and therefore cortisol — waking you up at night:
- "Establish a calming, consistent wind-down routine before bed. People can set aside 30 to 60 minutes to transition away from work, limit stimulating screen time, practice deep breathing or gentle stretching, and write down worries or next-day tasks to help clear their minds."
- "Maintaining a regular sleep schedule and creating a cool, dark, and comfortable bedroom can also support more restful sleep."
- "If someone wakes up with racing thoughts, instead of checking the clock or getting frustrated about being awake, they can try slow, steady breathing and gently redirect their attention to the present moment."
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