Cortisol and Sleep: Why Stress Keeps You Awake at Night

What does cortisol normally do across the day?

Cortisol is a hormone made by the adrenal glands, under the control of a brain-to-adrenal signaling loop called the HPA (hypothalamic-pituitary-adrenal) axis. It helps regulate blood sugar, blood pressure, inflammation and alertness, and it follows a daily rhythm:

• Morning: cortisol rises sharply in the first half hour or so after waking, helping you feel alert.
• Afternoon and evening: it gradually falls.
• Around bedtime and the first part of the night: it reaches its lowest point, which supports falling into deep sleep.
• Early morning hours: it begins to climb again in preparation for waking.

Cortisol isn’t a villain. Problems arise when the stress system stays switched on at times it should be quiet.

How stress and cortisol disrupt sleep

When you are stressed, the HPA axis and the “fight or flight” nervous system activate together: heart rate rises, the mind scans for problems, and the body is primed to stay alert. That is the opposite of what sleep needs. Your brain responds to a worrying email, a family conflict or tomorrow’s to-do list through the same systems it would use for a physical threat.

Research shows the link runs both ways:

• Insomnia is associated with a more active stress system. In a sleep-lab study, people with chronic insomnia secreted more cortisol and ACTH over 24 hours than good sleepers, with the biggest differences in the evening and first half of the night. The authors described insomnia as a state of hyperarousal, not just lost sleep.
• Lost sleep raises cortisol. In a classic study of healthy young men, one night of partial or total sleep loss raised cortisol levels the next evening by 37% to 45% and delayed its normal nighttime fall. The study was small and short-term, so the exact numbers shouldn’t be over-read, but it shows how quickly sleep loss can affect the stress system.

Why midlife women are especially affected

Several things converge in the 40s and 50s:

• Hormone changes. Estrogen and progesterone interact with the brain’s stress and sleep systems. Progesterone’s breakdown products act on the calming GABA system, and levels swing and then fall during perimenopause. Our guide to progesterone and sleep explains more.
• Night sweats. Hot flashes at night cause awakenings, each a small jolt to the stress system. A 2018 review found hot flashes are the biggest single contributor to sleep complaints in the menopause transition.
• Mood changes. Anxiety and depression become more common in the transition and are tightly linked to insomnia.
• Life load. Work, children, aging parents and the mental work of running a household often peak at the same time.

For how cortisol interacts with menopause more broadly, see cortisol and menopause.

Signs stress may be driving your sleep problems

• You feel “tired but wired” at bedtime.
• Your mind starts racing as soon as you lie down.
• You wake in the early morning hours and start problem-solving.
• Your sleep is worst during stressful weeks and better on vacation.
• You use alcohol or screens to switch off at night.

These patterns are common and don’t mean anything is medically wrong with your adrenal glands. They mean your stress response and your sleep are feeding each other.

Should you get your cortisol tested?

Usually not for sleep alone. Blood, urine and saliva cortisol tests exist to diagnose specific conditions:

• Cushing’s syndrome (too much cortisol), which causes features such as weight gain in the face and abdomen, purple stretch marks, easy bruising, muscle weakness, high blood pressure and high blood sugar.
• Adrenal insufficiency (too little cortisol), which causes fatigue, weight loss, dizziness and low blood pressure.

A systematic review of 58 studies found no evidence that “adrenal fatigue” is a real medical condition, and the saliva and urine panels often marketed for it give conflicting results. If you have features of the conditions above, a clinician can order the right tests. Our guide to high cortisol symptoms covers the warning signs.

What actually helps

Anchor your body clock

• Get up at the same time every day, including weekends.
• Get outdoor or bright light soon after waking.
• Dim lights and step away from work and news an hour or so before bed.
• Finish vigorous exercise earlier in the day if late workouts leave you wired.

Calm the stress response at night

• Slow, exhale-focused breathing. In a randomized study, five minutes a day of “cyclic sighing” (a double inhale through the nose, then a long, slow exhale) improved mood and lowered breathing rate more than mindfulness meditation over a month.
• Write tomorrow’s to-do list. In a sleep-lab study, people who spent five minutes writing a specific to-do list before bed fell asleep faster than those who wrote about tasks already done.
• Schedule worry time earlier in the evening, so bedtime isn’t when you first think things through.

Treat insomnia directly

If poor sleep has become a pattern, cognitive behavioral therapy for insomnia (CBT-I) is the first-line treatment recommended by the American College of Physicians. It targets exactly the hyperarousal and worry that keep the stress system going at night. See menopause insomnia for how it works.

Supplements

A meta-analysis of five trials found ashwagandha extract had a small benefit on sleep, mainly in people with insomnia at higher doses over eight weeks or more, but long-term safety data are limited and rare liver injury has been reported. Magnesium has weaker evidence. Check with a clinician before starting supplements, especially if you take other medicines, have thyroid or liver disease, or are pregnant.

Treat menopause symptoms that feed the loop

If night sweats are waking you, treating them removes one repeated trigger for the stress system. Hormone therapy is the most effective treatment for hot flashes and night sweats, and non-hormone prescriptions are available for women who can’t use hormones. Amie HRT+ is one option: a compounded estradiol and progesterone cream, with the strength chosen by a licensed clinician after an online review, for symptoms including night sweats and sleep disruption. It is not FDA-approved, it isn’t a treatment for stress or cortisol itself, and a clinician decides whether it is appropriate for you.

When to talk to a clinician