Cortisol is known as the stress hormone. It helps prime you for danger when your body’s flight-or-fight mode is activated. It can also be a good thing in times of eustress — or positive stress — as it gives you a short-term boost in energy and focus.
But if you have chronic stress — from endless work deadlines or a demanding toddler — you’ll have high levels of cortisol at all times, and this isn’t good news for your sleep. And as sleep loss can hike cortisol levels, it’s easy to get trapped in a vicious circle of more sleep loss and more cortisol.
But you don’t want constantly low cortisol levels either. Cortisol helps us wake up in the morning and feel alert. You just need the right amount of cortisol at the right times — but this is where things go wrong for many of us.
Below, we’ll answer every question you’ve ever had about cortisol and sleep. And we’ll explain how you can use the RISE app to lower your evening cortisol levels and get a good night’s sleep.
“Most of the time, you don’t need to know your exact cortisol levels," says Dr. Chester Wu. "But you do want to do healthy sleep and lifestyle habits to keep them in check. Try to maintain regular sleep patterns, get enough sleep each night, and keep stress levels low, especially before bed.”
Dr. Chester Wu is double board certified in Psychiatry and Sleep Medicine, and provides sleep medicine services, medication management, and psychotherapy to adults at his private sleep medicine and psychiatry practice.
Cortisol is a hormone that helps you feel alert. It helps you wake up in the morning and it’s a natural part of your body’s stress response, increasing your heart rate and helping you get ready to fight or run away from danger.
The hormone is produced by the hypothalamic pituitary adrenal axis (HPA axis), which is a part of both the central nervous system and the endocrine system. It’s made up of the adrenal glands at the top of your kidneys and the hypothalamus and pituitary gland in your brain.
The main roles of cortisol include:
When everything’s working well, your cortisol levels will naturally rise and fall over the course of the day and night. You want higher cortisol levels in the morning to help you wake up, and lower levels in the evening to help you fall asleep. This is part of the hormone's circadian rhythm, a roughly 24-hour cycle.
You’ll also have short-term high cortisol levels when you need to respond to a threat. Levels should return to normal when the stressor has passed. But many of us live in a constant state of high stress. And this is where sleep problems — and a whole host of other health issues — come in.
Normal cortisol levels will look a little different for everyone, and they even get higher as we age.
In general, they’ll be higher in the morning, peaking about 30 to 45 minutes after waking up. The early morning peak is part of what helps you wake up and it’s known as the cortisol awakening response (CAR). Cortisol levels will then gradually decrease as the day goes on, hitting their lowest at around midnight.
This rise and fall in cortisol will happen a little later in the day if you’re a night owl and earlier in the day for early birds. It also shifts earlier as we age.
In healthy adults who sleep from midnight to 8 a.m., normal levels of cortisol (measured in nanograms per deciliter) would look like this:
To find out if you have a cortisol imbalance, you’ll have to get your levels tested in a lab. Your cortisol levels can be measured through your saliva, urine, or blood. There are also companies that sell salivary cortisol or blood testing kits.
But for most of us, we don’t need to worry about the specifics. Some healthy lifestyle and sleep habits will help to rebalance your cortisol levels and your body should start producing the right amount at the right time. More on how to manage your cortisol levels soon.
We asked our sleep advisor and medical reviewer, Dr. Chester Wu, for his thoughts.
“Most of the time, you don’t need to know your exact cortisol levels. But you do want to do healthy sleep and lifestyle habits to keep them in check. Try to maintain regular sleep patterns, get enough sleep each night, and keep stress levels low, especially before bed.”
Cortisol isn’t the enemy of sleep. In fact, you need a healthy cortisol rhythm to keep your sleep cycle in check. But if cortisol levels are too high at the wrong times (i.e. in the evenings), you may have trouble sleeping.
Research shows a hyperactive HPA axis can lead to:
In short, yes. High cortisol levels in the evening can cause a lack of sleep. You might find it hard to drift off, wake up often during the night, or experience insomnia.
All this makes it harder to meet your sleep need — which is the genetically determined amount of sleep you need. And when you don’t meet your sleep need, you start building up sleep debt, the running total of how much sleep you owe your body.
High sleep debt can lead to low energy, poor mood, trouble focusing, and mental and physical health problems.
Not sure how much sleep you need each night? RISE can work out your unique sleep need and whether you’re carrying any sleep debt.
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The sleep loss and cortisol connection goes both ways. Sleep loss is a stressor on the body, so missing out on shut-eye can increase your cortisol levels.
You don’t need to pull an all-nighter to see the effects — although that can hike your cortisol levels. A 2021 review highlights multiple studies showing that partial sleep deprivation can lead to an increase in next-day cortisol levels.
Even getting 5.5 hours of sleep — something some of us do during the workweek — can cause an increase in cortisol levels the next evening.
As well as not getting enough sleep overall, sleep disturbances like waking up in the night (which high cortisol can cause) is also a stressor and this can trigger more cortisol production.
High cortisol levels can be caused by:
We’ve covered more on what causes high cortisol levels here, including why it’s so dangerous.
The symptoms of high cortisol levels include:
Poor sleep, as a result of too much cortisol, inflates your sleep debt and deflates your next-day energy levels. But that’s not all.
High cortisol levels can also lead to an increased risk of cardiovascular events, including heart attacks and stroke. And that’s not to mention the many many ill effects of sleep deprivation, like type 2 diabetes, heart disease, and early death.
The symptoms of low cortisol levels include:
Low cortisol levels can be caused by adrenal insufficiency, which can come from Addison’s disease or a tumor on the pituitary gland. Depression is also linked with a blunted CAR, which can make it harder to get up in the morning and it’s a risk factor for insomnia. And finally, sleep deprivation can increase your evening cortisol levels, but decrease your morning cortisol levels.
Speak to your healthcare provider if you think you have low cortisol levels.
You want higher cortisol levels in the morning. This helps you wake up, shake off sleep inertia (or grogginess), and feel alert as you head into the day.
You can increase morning cortisol levels by:
Both caffeine and exercise are great for a morning boost, but they can keep you up at night if you don’t get the timings right. RISE can tell you when to avoid caffeine and late workouts to make sure they don’t disrupt your sleep.
High cortisol levels can lead to and be caused by sleep deprivation, but what about sleep disorders? It turns out there’s a link there, too.
High cortisol levels may cause chronic insomnia. Research shows patients with insomnia without depression have high cortisol levels, especially in the evening and when they go to sleep.
The paper states excess HPA axis activation may cause insomnia or keep chronic insomnia going.
Obstructive sleep apnea is when your breathing is cut off temporarily in your sleep. When your brain notices low oxygen levels, it wakes you up to kickstart your breathing.
These nighttime awakenings may cause a spike in cortisol. There is some research showing those with sleep apnea have elevated cortisol levels, but more research is needed in this area.
High cortisol levels are also linked to obesity, which is a risk factor for sleep apnea.
High cortisol levels at night keeping you awake? Here’s how to reduce them quickly and naturally.
You don’t want chronically low cortisol, though. You need the hormone for proper immune function, metabolism, and to wake up effectively. We’ve covered more on how to lower cortisol here, including when you don’t want to lower it.
High cortisol levels are linked to obesity and weight gain, especially belly fat. High levels of the hormone can lead to overeating, high blood sugar levels, and sleep problems (which also contribute to weight gain).
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But you can break the link. You can stop cortisol weight gain by:
Want more weight loss tips in the face of high cortisol? We deep dive into how to stop cortisol weight gain here.
High cortisol levels aren’t always a bad thing. Cortisol helps you feel alert in the morning and handle stressful situations. But when cortisol is constantly high, your sleep can be impacted. Plus, it’s all too easy to slip into a vicious circle of sleep loss and increased cortisol levels.
Use the RISE app to break the cycle. RISE can tell you how much sleep debt you have and keep track of it as you pay it back. The app can also predict your circadian rhythm, so you can stay in sync, and coach you through 20+ sleep hygiene habits, to make falling asleep easier to do.
It’s fast, too: 80% of RISE users feel the benefits within five days, so you could be sleeping better within the week.
High cortisol levels have been linked to insomnia, waking up during the night, and less sleep time overall. When cortisol levels are normal, the hormone helps you wake up in the morning (when levels are higher) and drift off at night (when levels are lower).
High cortisol levels later in the day and near your bedtime trigger insomnia and other sleep problems. That's because cortisol is an alertness-boosting hormone.
The symptoms of high cortisol at night include insomnia, waking up throughout the night, increased urination, weight gain, depression, thin skin, and high blood pressure.
Prevent cortisol spikes at night by keeping stress low, getting enough sleep, staying in sync with your circadian rhythm (or body clock), avoiding late-night intense exercise, and eating a healthy diet.
Low cortisol levels in the evening can help you fall asleep. Keep cortisol levels in check by keeping stress low, getting enough sleep, staying in sync with your circadian rhythm (or body clock), avoiding late-night intense exercise, and eating a healthy diet.
High cortisol levels can mess with your hunger, metabolism, and sleep — all of which can lead to weight gain. Keep cortisol levels in check by keeping stress low, getting enough sleep, staying in sync with your circadian rhythm (or body clock), avoiding late-night intense exercise, and eating a healthy diet.
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