What Does Cortisol Do?
Cortisol is a stimulating, alerting hormone and the body’s primary stress hormone, driving the body’s fight-or-flight response in the presence of a threat or stressor. But cortisol does more than spur fight-or-flight. This hormone has a number of other functions, including:
- Regulating blood pressure
- Balancing blood sugar
- Influencing inflammation
- Regulating energy levels
- Contributing to cardiac system function
- Helping to control the sleep-wake cycle
Cortisol gets a pretty bad rap, and there’s no question that chronically elevated cortisol contributes to sleep disruptions and other health problems. But cortisol is an essential component of human physiology. The challenge for many of us is to keep cortisol levels from getting too high. (As you’ll see, sleep can help with that).
When cortisol is elevated too frequently and over long periods of time, it can cause a number of health problems. They include:
- Chronic illnesses, including high blood pressure, diabetes, and heart disease
- Weight gain (both by stimulating appetite and by encouraging the body to store fat)
- Fatigue
- Brain fog and difficulty with memory and focus
- Compromises to the immune system, leading to greater risk of illness
- Increased inflammation and other effects of aging
- Problems with digestion
- Mood disorders, including depression and anxiety
- Sleep problems
How Does Cortisol Affect Sleep?
Like most hormones, cortisol follows a natural 24-hour cycle. Levels begin rising during the second half of the night, peak in the morning to help you wake up, and gradually decline throughout the day. By bedtime, cortisol levels are typically at their lowest, helping prepare your body for sleep.
This daily cortisol rhythm is true for most chronotypes: lions, bears, and wolves. In dolphins, however, the cortisol rhythm is inverted. Dolphins have cortisol on the rise at night and reaching its lowest levels in the morning. This inverted cortisol rhythm contributes to difficulty falling asleep, restless and light sleep, groggy mornings, and daytime fatigue.
Research shows a complex two-way street between this cortisol rhythm and sleep. Poor, insufficient, irregular sleep increases cortisol activity, leading to more stress and greater risk of health complications. And heightened cortisol activity is linked to more restless and fragmented sleep, less slow wave sleep, and lower overall sleep amounts. It can be a vicious cycle.
Does Cortisol Cause Sleep Disorders?
One big question is this: Does too-high cortisol cause sleep disorders such as insomnia and sleep apnea, or is high cortisol a result of those sleep disorders? The answer is complex, and one that scientists are still reaching for. We don’t yet fully understand the directionality of the relationship between sleep disorders and cortisol. The short answer is, it’s likely some of both.
High cortisol levels frequently appear with insomnia. But it’s not clear whether elevated cortisol is a cause or consequence of insomnia. It’s entirely possible that, depending on an individual’s circumstances, cortisol could be both a cause and a consequence.
Obstructive sleep apnea (OSA) is another sleep disorder with links to cortisol. Elevated cortisol levels are often present in people with sleep apnea, but it’s not clear that cortisol contributes directly to sleep apnea. Research does indicate that elevated cortisol can result from the sleep loss, arousal, and compromised breathing that characterizes sleep apnea.
There’s also evidence that high cortisol may contribute to the metabolic complications that accompany sleep apnea, including diabetes. It’s still unclear if it’s the sleep deprivation from the undiagnosed apnea, that’s raising your cortisol levels or it’s the apnea itself.
High cortisol is also associated with obesity, as well as depression, anxiety, and other stress-related mood disorders. These are conditions that are often contribute to and occur alongside insomnia and sleep apnea. They’re also conditions that are strongly associated with poor sleep, even in the absence of a sleep disorder.
Don’t Just Test Your Sleep. Understand It.
Measure key sleep metrics and review your results with a licensed sleep-care provider. Discuss sleep issues and options to make restless nights a thing of the past.
How to Improve Cortisol Levels Naturally
Keeping cortisol levels in check can contribute to healthier sleep. Of course, sleeping better — making enough time for nightly sleep, adhering to a consistent sleep routine, practicing other fundamentals of sleep hygiene — is one way to lower cortisol. Here are others:
Get Regular, Light-to-Moderate Exercise
Research shows light to moderate exercise doesn’t create a short-term spike in cortisol like intense exercise can, and it also can reduce cortisol levels overall. Yoga and tai chi, two fantastic and gentle mind-body exercises for sleep, have been shown in scientific studies to lower cortisol.
Manage Stress With Mindfulness and Breath
Deep breathing exercises can reduce cortisol, studies show. Developing mindful awareness about our own stress and its triggers helps to relieve that stress, and reduce cortisol. Research shows that mindfulness-based stress reduction lowers cortisol in the body.
Changing patterns of negative thinking can also reduce cortisol. Negative, angry, self-critical thoughts can lead to cortisol spikes, but studies show when we address these thinking patterns, and employ positive thinking in their place, cortisol levels go down.
Consider Supplements
Several supplements that may help sleep also may help lower cortisol. Elevated cortisol is associated with deficiencies in omega-3 fatty acids, and research suggests omega-3 fatty acids may improve cortisol levels. L-theanine and magnesium, two natural supplements that have demonstrated benefits for sleep, may also help to keep cortisol at healthy levels.
