Is Cortisol The Reason You Keep Waking Up At 3 A.M.?

Waking up in the middle of the night and not being able to fall back asleep can be extremely frustrating, regardless of whether your throbbing bladder or snoring partner is to blame. But perhaps even more annoying is waking up for no apparent reason.

Sleep scientists have been studying what triggers such disrupted sleep for decades and still haven’t come up with solid answers. TikTokers, however, say they’ve uncovered the culprit — cortisol.

Video after video accuses cortisol, better known as the stress hormone, of causing a host of health issues, including but not limited to weight gain, acne, low libido, and of course, difficulty sleeping. Those nights you spend tossing and turning after randomly waking up at 3 a.m., people on social media say, are likely due to bursts of cortisol coursing through your veins.

Turns out the TikTok wellness gurus may not be totally wrong. Cortisol does help regulate our sleep-wake cycle; namely, it gets us up in the morning, thanks to its stimulating effects on the brain. But the impact that cortisol has on sleep, and the role it may play in waking us up in the middle of the night, is much more complicated than you think.

“Unfortunately, it’s not that clear-cut,” says Dr. Jocelyn Cheng, a neurologist in epilepsy and sleep medicine and vice chair of the public safety committee at the American Academy of Sleep Medicine. “Sleep health is multifactorial, and attributing one specific cause for either a problem or a benefit oversimplifies it.”

What Exactly Does Cortisol Do?

Cortisol is your main stress hormone, but it’s really a jack of all trades. When balanced, it also helps control metabolism, maintain blood pressure, lower inflammation, and regulate blood sugar. A more fitting name for cortisol would be “the energizing hormone,” says Mark Wetherell, a professor of health psychobiology at Northumbria University in the United Kingdom who studies how stress impacts health.

Cortisol works by redirecting resources, aka energy, from certain parts of the body, such as the immune, digestive, and reproductive systems, to help you respond to stimuli, both good and bad, Wetherell says. It’s what helps you feel alert when you hear a strange noise in your backyard or win a prize at a carnival.

In excess, cortisol can cause rapid weight gain, diabetes, muscle weakness, and skin that bruises easily, according to WebMD. Too little cortisol can lead to fatigue, loss of appetite, low blood pressure, diarrhea, and more.

In other words, cortisol drives your flight-or-fight response via a complex network called the HPA axis (hypothalamic-pituitary-adrenal axis). When triggered, this HPA axis sends instructions to your brain to release cortisol (among other hormones like adrenaline), causing rapid heart rate and breathing, as well as sharpened senses.

“This is all fine in the short term and precisely what the system is designed to do, but if we get stressed too often or for too long, these systems become faulty and this can lead to the long-term problems we associate with stress,” Wetherell says, such as illness, infertility, digestive issues, and yes, problems sleeping.

The Relationship Between Cortisol & Sleep

Guided by the sun’s rise and fall, your sleep-wake cycle follows a 24-hour clock, or circadian rhythm, that tells your body when it’s time to sleep and time to be awake. Cortisol secretion follows a similar 24-hour cycle.

Generally, cortisol levels will drop to their lowest around midnight, increase around two to three hours after falling asleep, and then keep rising until they peak around 9 a.m. (or about an hour after you wake up). Meanwhile, the sleep-promoting hormone melatonin increases and decreases on the opposite schedule.

Outside of this biological clock, cortisol naturally drops throughout the day and fluctuates frequently in response to anything that stimulates you. But stress can throw its circadian rhythm off its tracks. As a result, cortisol levels may be higher than they should at night, making you jittery and unable to fall or stay asleep. This is common among people with insomnia, a sleep disorder that affects nearly 30% of Americans.

Still, the reason you wake up in the middle of the night involves more than just high cortisol levels, says Cheng, who says this is a classic “chicken and egg question.”

The relationship between the HPA axis and sleep is bi-directional. This means that stress can lead to poor sleep and poor sleep can lead to stress, a brutal feedback loop that clouds the root cause of your midslumber restlessness.

Scientists have yet to figure out how that complex two-way street influences the development of sleep disorders — does high cortisol cause insomnia or sleep apnea, for example, or is high cortisol a result of those disorders? — says Ivan Vargas, a licensed clinical psychologist and assistant professor of psychological science at the University of Arkansas who studies the role cortisol plays in keeping us up at night. (It’s likely a combination of both, experts agree.)

Vargas hypothesizes that, at least for people with insomnia, nightly tosses and turns may be an overly sensitive response to the short bursts in cortisol that naturally occur when our bodies enter a state of wakefulness.

“In those lower levels of wakefulness when we’re not fully awake, one person who’s a good sleeper might be able to fall right back to sleep,” Vargas says. “But someone with insomnia may be primed to respond to even those low levels of wakefulness where their body is like, ‘Oh, we are waking up — burst of cortisol.’”

It’s also possible that some of us might anticipate the stress of not being able to fall or stay asleep as night time approaches, Vargas says, which could lead to a rise in cortisol that may make us restless.

“Sleep is just a much more complicated process than whether or not you're awake or asleep,” Vargas says. “This is incredibly understudied, so we still have more questions than we do answers.”

When and how much cortisol is released also depends on how long your body is under stress. People who experience short-term stressors like failing an exam will be able to return to their normal circadian rhythm, Cheng says. But those with more chronic stress, say a toxic relationship with the in-laws, may experience long-term changes to their cortisol’s internal clock that negatively impact sleep quality.

Cortisol Isn’t The Villain Here

Elevated cortisol undoubtedly affects the quality of your sleep, which makes it an easy target to blame all of your health problems on. But it’s important to remember that your behavior is likely the reason you may have elevated cortisol in the first place.

“Most of us have really horrible sleep hygiene. We expose ourselves to bright lights at night as we scroll through our phones, go to bed at different times every day, and exercise too close to bedtime,” Cheng says. “For the regular healthy person, those are typically the reasons why you’re not waking up or going to sleep when you want to.”

“I would not get fixated on any one particular hormone because there’s a whole lot going on,” she adds.

A laundry list of other factors can affect your stress and sleep quality, including health conditions like depression and fibromyalgia, your menstrual cycle, and certain medications you may be taking.

Michael Breus, a clinical psychologist known as “The Sleep Doctor,” agrees that “elevated cortisol levels are mostly self-induced.” But he says the desire for a quick fix that people on social media swear by is rooted in misunderstanding.

After all, the goal isn’t to wipe out cortisol entirely; it’s to find a balance and ultimately change your lifestyle habits for the better.

“Social media kind of blows things out of proportion. Cortisol is good. If we didn’t have it, we wouldn’t wake up in the morning. But it needs to be in some level of balance, which social media really misses,” Breus says. “People need to understand that there are things they can do to help manage that.”

Breus recommends these tips for lowering cortisol levels and reducing its impact on sleep quality:

• Avoid caffeine late at night, and wait at least 90 minutes after waking up before having coffee or tea, as it can “extend the cortisol effect.”
• Take a cold shower in the morning, which may help lower cortisol levels throughout the day.
• Deep breathing exercises throughout the day or before bed, using techniques like the 4-7-8 method (breathe in for four seconds, hold for seven seconds, and breathe out for eight).
• Avoid a high sugar or processed diet, and prioritize more whole foods.
• Exercise regularly, but avoid intense workouts at night.

Experts:

Michael Breus, clinical psychologist

Dr. Jocelyn Cheng, neurologist in epilepsy and sleep medicine and vice chair of the public safety committee at the American Academy of Sleep Medicine

Ivan Vargas, licensed clinical psychologist and assistant professor of psychological science at the University of Arkansas

Mark Wetherell, professor of health psychobiology at Northumbria University in the United Kingdom