The Tug of War Between Melatonin and Cortisol

Alarm Clock Next to Insomniac
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When you are overwhelmed by stressful events, the cause of your sleeplessness is obvious. As soon as your head hits the pillow, the quiet inactivity of the night lets your worries spin out of control, setting your mind ablaze. Even if you somehow drift off in brief period of fitful, restless sleep, you are gripped with the same anxious thoughts as soon as you awaken, making it nearly impossible to return to sleep.

But what about the times when you are not surrounded by a wall of worry on a nightly basis? You feel comfortable and relaxed as you crawl into bed and close your eyes, but sleep remains elusive. You know that you are not thinking of anything stressful as you count sheep or backwards from 1000, but sleep never seems to come. What is preventing you from drifting off to dreamland?

The simple answer rests in the role of melatonin in your body's sleep-wake cycle. The production of melatonin, a natural hormone that signals to the body that it is time for sleep, can be interrupted by a number of external factors, such as artificial light and your dietary choices. To combat this, limit electronic device use before bed and avoid caffeine, alcohol, and heavy meals late in the evening.

However, melatonin is only part of the equation. Dysregulation of another hormone that is essential to your sleep-wake cycle can counteract the sleep-inducing effects of healthy melatonin levels.

Balance Between Melatonin and Cortisol
Credit: Dreamstime

Released as part of your fight-or-flight mechanism, cortisol is your body's primary stress hormone. This key natural hormone regulates and modulates many of the changes in bodily processes that occur when a stressor is introduced to your environment. Levels of cortisol are typically at their lowest in the middle of the night, when levels of melatonin are high. Likewise, cortisol levels peak about 20 to 30 minutes after we wake, when levels of melatonin are low. In this way, cortisol serves as a counterbalance to melatonin, keeping your body awake, alert, and ready for action.

Although cortisol and melatonin are both central to a healthy sleep cycle, daily persistent stress can upset the delicate balance between these two hormones. Even if you do your best to unwind in the evening, constant pressure from work and family throughout the day can result in chronically high cortisol levels. A range of negative side-effects are associated with this condition, including a pronounced inability to sleep. To prevent cortisol from interfering with your sleep-wake cycle, it is essential to keep daily stress to a minimum.

Consider making more time to engage in physical activities or hobbies that relax you or spending more time with people you love and care about. Simple changes to your daily routine such as these can help take your mind off your worries, helping restore balance to your body's natural levels of cortisol and melatonin, keeping you calm throughout the day and sleeping peacefully throughout the night.



Paul has been interested in medical research since his first organic chemistry class in college. He was a high school biology teacher for 32 years until retiring to spend more time reading, hiking, and camping with his wife and two dogs.

Email Paul at [email protected].


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