Cortisol and Sleep: What You Need to Know

Cortisol is an important hormone for your body. It helps manage your stress and affects how you deal with daily challenges. Cortisol also plays a role in your sleep-wake cycle, helping you wake up in the morning and sleep well at night. 

When cortisol levels stay high because of stress or other reasons, it can make it hard to fall asleep and stay asleep. On the other hand, if cortisol levels are too low for a long time, it can also disrupt your sleep, leaving you tired and unable to recover.

Keeping cortisol levels balanced is crucial for your overall health and getting good sleep.

What is cortisol?

Cortisol is a steroid hormone made by your adrenal glands, which are located above your kidneys. 

It is often called the stress hormone because your body produces more of it during stressful times. However, cortisol does more than just respond to stress. It helps to:

• Regulate blood sugar

• Control blood pressure

• Manage energy and metabolism

• Reduce inflammation

• Play a key role in your sleep-wake cycle

Cortisol levels change throughout the day. They are highest in the morning and lowest at night.

How does cortisol regulate sleep and waking?

Cortisol and melatonin play important roles in managing your sleep-wake cycle. When cortisol is high, melatonin is low, and when cortisol drops, melatonin levels rise.

Why cortisol rises in the morning

Cortisol levels peak about 30 to 45 minutes after you wake up. This is called the cortisol awakening response (CAR).

This natural rise in cortisol helps you feel awake and energized as you start your day. Higher cortisol levels improve your mood and boost your cognitive function, preparing your body and mind for daily activities.

Why cortisol drops at night

Cortisol levels decrease throughout the day and reach their lowest point around midnight. This drop in cortisol allows melatonin to rise, which helps your body prepare for sleep. If cortisol stays high at night, this process doesn't work as it should.

How cortisol and melatonin work together

Melatonin signals to your brain that it's time to sleep. The pineal gland produces melatonin. High levels of cortisol block melatonin production. When cortisol drops in the evening, the pineal gland can release melatonin. The timing of cortisol changes is as important as the amount.

If cortisol remains high at night, melatonin cannot rise, making you feel tired but unable to fall asleep.

What controls this cycle

Three parts of your body work together to control cortisol production:

• Hypothalamus: Monitors cortisol levels and releases corticotropin-releasing hormone (CRH) when levels drop

• Pituitary gland: Releases adrenocorticotropic hormone (ACTH) in response to CRH

• Adrenal glands: Produce cortisol in response to ACTH

This system is known as the hypothalamic-pituitary-adrenal axis or HPA axis. Light exposure and your internal body clock (circadian rhythm) also affect when cortisol rises and falls.

What happens to your sleep when cortisol is too high at night?

High cortisol levels at night can disrupt sleep in many ways.

You have trouble falling asleep

High cortisol keeps your body in a state of alertness, known as the fight-or-flight response. This makes your heart rate and blood pressure stay high, and your mind remains active. When this system is on, your body cannot relax into sleep.

You wake up during the night

In some cases, cortisol can rise during sleep if blood sugar drops too low, particularly in people with diabetes or those who skip meals. Your body releases cortisol to raise blood sugar levels back to normal.

You might wake up suddenly with a fast heartbeat, feeling anxious or worried. It can be hard to fall back asleep because cortisol is now high.

Your sleep is light or fragmented

High levels of cortisol, especially in the evening and night, are associated with reduced deep sleep. Deep sleep is important because it helps your body repair tissue, build muscle, and strengthen your immune system.

If you don't get enough deep sleep, you may wake up feeling tired even after seven or eight hours in bed. 

This can lead to feeling exhausted during the day but unable to sleep at night, which is sometimes called "tired but wired."

Also Read: This Common Habit Makes Insomnia Worse

What happens to your sleep when cortisol is too low?

Low cortisol affects sleep differently than high cortisol levels.

Typically, the morning increase in cortisol helps you wake up. However, when cortisol levels are low, you may experience chronic fatigue, weakness, dizziness (especially when standing), low blood pressure, weight loss, and cravings for salty foods.

You might experience grogginess regardless of how long you sleep, making mornings particularly challenging. Throughout the day, your energy levels remain low, and sleep may not feel refreshing. As a result, you can feel tired no matter how much rest you get.

People with low cortisol may also experience poor sleep quality, insomnia, and other sleep disturbances, even with treatment.

Consistently low cortisol is referred to as adrenal insufficiency, a condition that requires medical treatment. Adrenal insufficiency can be primary (when the adrenal glands don't produce enough cortisol, also known as Addison's disease) or secondary (when the pituitary gland doesn't produce enough ACTH to stimulate the adrenals). Untreated adrenal insufficiency can lead to life-threatening complications.

How does the cortisol-sleep connection affect weight?

Cortisol, sleep, and weight all affect each other.

When cortisol levels are high, your body tends to store fat, especially around your waist. It also makes you feel hungrier and crave unhealthy foods, particularly high-calorie, sweet, fatty, and salty foods.

Not getting enough sleep can raise evening cortisol levels and disrupt normal cortisol patterns. It also disrupts hunger hormones. Ghrelin, which makes you feel hungry, increases. Leptin, which tells you when you're full, decreases. This makes you feel hungrier and less satisfied after eating.

High cortisol can disrupt sleep, and when we don’t sleep well, cortisol levels go up even more. This leads to more fat storage and a greater appetite. Not getting enough sleep can also cause you to eat over 250 extra calories a day, mainly by snacking on high-calorie foods like sweets, chips, and other salty snacks.

Research shows that very short sleep duration (less than 5 hours) is associated with higher cortisol levels, particularly in the evening.

Also Read: Best Foods for Sleep: What to Eat and Avoid Before Bed

What causes cortisol to disrupt your sleep?

Several things can keep cortisol levels high when they should be low:

• Chronic stress: Ongoing stress keeps the HPA axis active, stopping cortisol from decreasing at night.

• Caffeine: Caffeine stimulates cortisol release, and its effects can last for several hours. Since caffeine has a half-life of about 5-6 hours, afternoon coffee can still affect your sleep at night.

• Alcohol: Alcohol raises cortisol levels and disrupts sleep, which can make you wake up during the night.

• Blue light from screens: Blue light tells your brain it is daytime, which lowers melatonin production and interrupts your sleep-wake cycle.

• Late-night intense exercise: Vigorous workouts can raise cortisol levels temporarily. Exercising close to bedtime can keep levels high and interfere with sleep.

• Irregular sleep schedule: An inconsistent sleep schedule disrupts your body’s natural clock and flattens your cortisol patterns.

• Blood sugar swings: Eating refined carbs or sweets before bed can cause your blood sugar to spike and crash, which triggers cortisol release.

What are the signs of a cortisol-related sleep problem?

Signs you might notice include:

• Feeling tired during the day but wide awake at night

• Taking a long time to fall asleep, even when you're tired

• Waking up between 2 and 4 AM and having trouble falling back asleep

• Waking up with a racing heart or feeling anxious

• Not feeling rested after seven to eight hours of sleep

• Having trouble concentrating or feeling foggy during the day

• Struggling to wake up in the morning, no matter how long you slept

High cortisol symptoms in women

When cortisol levels remain chronically elevated in women, additional symptoms may appear beyond sleep problems:

• Weight gain, particularly in the face and belly

• Irregular or missed periods

• Facial hair growth or acne

• Thinning hair on the scalp

• Low sex drive

• Mood changes, anxiety, or depression

When to see a doctor: If you experience several of these symptoms together, especially weight gain in the face and abdomen, combined with sleep problems, consult your healthcare provider. These symptoms may indicate underlying medical conditions such as Cushing's syndrome, polycystic ovary syndrome (PCOS), or thyroid disorders that require proper diagnosis and treatment.

Other Medical conditions affecting cortisol

There are two main conditions related to abnormal levels of cortisol, a hormone produced by the adrenal glands.

Cushing syndrome

Cushing syndrome occurs when your body is exposed to high levels of cortisol for an extended period.

Causes:

• Corticosteroid medications: The most common cause is long-term use of corticosteroid medications, such as prednisone, often prescribed for asthma, rheumatoid arthritis, or lupus.

• Cushing's disease: A pituitary tumor produces excess ACTH (adrenocorticotropic hormone), which signals the adrenal glands to make too much cortisol. This accounts for about 70% of endogenous (internal) cases.

• Adrenal tumors: Tumors on the adrenal glands themselves can produce excess cortisol.

Symptoms include:

• Weight gain in the face (moon face) and abdomen (central obesity)

• Purple or pink stretch marks (striae) on the skin

• Muscle weakness, particularly in the upper arms and thighs

• High blood sugar and increased risk of diabetes

• High blood pressure

• Thinning skin that bruises easily

• Bone loss (osteoporosis)

Addison's disease and adrenal insufficiency

Addison's disease occurs when the adrenal glands do not produce enough cortisol.

Types:

• Primary adrenal insufficiency (Addison's disease): The adrenal glands themselves are damaged, usually because the immune system attacks them. This is the most common cause in developed countries, accounting for 70-90% of cases.

• Secondary adrenal insufficiency: The pituitary gland does not release enough ACTH to signal cortisol production. The most common cause is long-term use of corticosteroid medications that suppress the body's natural hormone production.

Symptoms include:

• Severe, persistent fatigue and weakness

• Unintentional weight loss

• Low blood pressure and dizziness, especially when standing

• Cravings for salty foods

• Darkening of the skin (hyperpigmentation), especially in primary adrenal insufficiency

• Nausea, vomiting, and abdominal pain

Both conditions require medical diagnosis and treatment. If left untreated, they can lead to life-threatening complications. If you suspect you may have symptoms of either condition, consult your healthcare provider for proper evaluation and testing.

Also Read: Harvard Researchers Find that a Good Night’s Sleep Can Add Years to Your Life

How can you support healthy cortisol levels for better sleep?

Here are simple ways to help support healthy cortisol levels at night:

1. Keep a consistent sleep schedule. Go to bed and wake up at the same time every day, even on weekends.

2. Get morning light exposure. Bright light in the morning helps strengthen your natural cortisol rhythm, supporting higher levels in the morning and proper decline at night.

3. Limit caffeine after noon. Caffeine can stay in your body for a long time, meaning coffee at 2 PM can still affect you at 8 PM.

4. Avoid alcohol close to bedtime. Alcohol disrupts sleep quality and raises cortisol levels during the night.

5. Turn off screens 60 to 90 minutes before bed. Blue light from screens suppresses melatonin production and disrupts your natural sleep-wake cycle. If you must use devices, consider using a blue light filter.

6. Practice controlled breathing. Slow breathing helps you relax. One technique is the physiological sigh: inhale twice through your nose, then exhale slowly through your mouth.

7. Write down tomorrow's tasks before bed. This helps get worries off your mind and allows your brain to relax.

8. Consider a natural sleep aid. Sip2Sleep® combines Montmorency tart cherry extract, which has been shown to increase melatonin levels naturally and improve sleep duration, with Rafuma Leaf (Venetron®), a clinically studied botanical that promotes relaxation and supports deep sleep without causing next-day drowsiness.

Takeaways

Cortisol is a hormone that is essential for waking up, dealing with stress, and staying alert during the day.

When cortisol levels go out of balance due to long-term stress, an unhealthy diet, or medical issues, sleep can be affected. Poor sleep can, in turn, make cortisol levels worse. To break this cycle, you need to manage stress and improve your sleep habits.

For extra help, Sip2Sleep provides a synthetic melatonin-free option that supports your body's natural melatonin production and sleep-wake cycles.

If lifestyle changes don't improve your sleep after several weeks, talk to your healthcare provider.

Disclaimer: This article is for information and education only. It is not medical advice. Do not use this information to diagnose or treat any health problem or disease. Always talk to your healthcare provider before changing your health routine or if you think you have a medical issue.

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