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, cortisol, and the HPA axis. The short answer is that it’s likely some of both. That’s the two-way relationship in action.
Research shows that heightened HPA-axis activity is linked to more restless, fragmented sleep, less slow-wave sleep, and lower overall sleep amounts. This strongly suggests a role for cortisol as a sleep disruptor. Research including this 2014 study shows that sleep deprivation is linked to higher cortisol levels and to a more extreme cortisol response in the presence of stress—that’s the HPA axis going into action urging the body into a state of fight-or-flight. This strongly suggests a role for sleep problems as aggravators of cortisol. And other research shows links between compromised sleep quality and heightened HPA axis activity.
What about specific sleep disorders, such as insomnia? High cortisol levels frequently appear with insomnia. But it’s not clear whether elevated cortisol is a cause or consequence of insomnia. And it’s entirely possible that depending on an individual’s circumstances, cortisol could be both a cause and a consequence.
Obstructive sleep apnea 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, and heightened activity of the HPA axis, can result from the sleep loss, arousal, and compromised breathing that characterizes sleep apnea. There’s also evidence that high cortisol and overactive HPA-axis activity 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 if it’s the apnea itself.
High cortisol is associated with obesity, as well as depression, anxiety, and other stress-related mood disorders. These are conditions that 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 clinically formal sleep disorders.
We’ve got more work to do to better understand the mechanisms by which cortisol affects sleep. It is already clear, however, that disordered sleep and out-of-balance cortisol frequently go hand-in-hand. Tending to sleep problems is one important way to help bring cortisol levels back into line while improving your nightly rest and lowering your risk for illness, both physical and psychological.
What to remember: High cortisol may be a consequence of common sleep disorders, including insomnia and sleep apnea. It also may be a contributor to sleep disorders. And it’s a contributor to other health problems (weight gain, stress) that undermine healthy sleep.
How to improve cortisol levels, naturally
Keeping cortisol levels in check—and HPA axis activity from ramping up too high—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:
Practice 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. A positive outlook is also linked to better sleep, as I’ve talked about before. And mindfulness is a powerful contributor to healthy sleep, as you’ve heard me talk about frequently.
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 HPA-axis functioning at healthful levels, and thereby keep cortisol levels in check.
Don’t stress about cortisol. Take steps to manage it. Sleep is both a tool and a beneficiary of attention to keeping stress in check and cortisol levels healthy.
Michael J. Breus, Ph.D., DABSM