Which Hormones Affect Sleep?
The human body is sustained by trillions of biochemical reactions, with hormones acting as chemical messengers. When your hormones are irregular, this wreaks havoc on your body and can impact sleep.
Certain hormones play a critical role in regulating sleep, such as melatonin, which shapes and shifts the timing of your circadian rhythm (body clock), and cortisol, which is accompanied by adrenaline and noradrenaline, increasing your heart rate and temperature.
This article introduces the link between hormones and sleep, with links to studies and research for further reading.
Let's jump in!
What hormones impact sleep?
Three essential hormones impact sleep:
- Melatonin (sleep hormone)
- Cortisol (stress hormone)
- Serotonin (mood-regulating hormone)
These three hormones are intertwined and can impact one another, so linking sleep problems to specific hormones is not an exact science.
Melatonin and sleep
Melatonin is known as the sleep hormone. It regulates your sleep-wake cycle, with your body releasing more during the evening (or when your body thinks it's time for sleep, which can get knocked out of whack).
Darkness prompts the production of melatonin in healthy people, with light halting its release. As such, it is essential for a healthy sleep-wake cycle. Your body produces melatonin naturally – problems with its production can cause sleep problems like insomnia and make falling asleep more difficult.
You can also get melatonin supplements, although doctors do not widely recommend these. Melatonin supplementation for sleep disorder treatment shows mixed results, with this meta-analysis showing mildly beneficial effects.
What causes melatonin irregularities? The most common causes include a poor sleep schedule and the blue light emitted from devices. Insomnia also wreaks havoc on melatonin, knocking your sleep patterns out of whack.
Cortisol and sleep
The HPA axis produces the stress hormone cortisol, which helps to coordinate your sleep-wake cycles. Elevated cortisol causes sleep disturbances by stimulating wakefulness and reducing melatonin production.
Stress and anxiety trigger cortisol release, accompanied by the release of adrenaline and noradrenaline, increasing your energy levels, heart rate, and body temperature. The adrenaline rush fuels stress and anxiety, making it difficult to fall asleep and impacting your circadian rhythm.
Because cortisol has powerful effects on sleep, dealing with stress, anxiety, and depression is the best way to keep it in check. This study found that people with depression have higher cortisol levels in the evening and at sleep onset.
Cortisol levels rise when you are stressed and anxious, and cortisol levels are too low when your adrenal glands don't operate normally. For example, COVID-19 has recently been found to cause adrenal insufficiency.
Serotonin and sleep
Serotonin is a mood stabilising hormone, with heightened levels linked to a reduction in REM sleep (the most important of the four sleep stages). Conversely, low levels of serotonin are linked with depression and insomnia.
Serotonin is a mood stabilising hormone, with heightened levels linked to a reduction in REM sleep (the most important of the four sleep stages). Conversely, low levels of serotonin are linked with depression and insomnia.
When serotonin levels are kept in check, it performs the essential role of regulating your sleep cycle by promoting wakefulness and inhibiting REM sleep. Serotonin is only a problem when levels drop low or go too high. Low serotonin levels are more common, stimulating some people's sleeplessness, low mood, and fatigue.
Your body regulates serotonin while sleeping, using it to trigger wakefulness. It is also a precursor for melatonin, helping regulate your circadian rhythm.
Most serotonin problems are caused by drugs/substances like caffeine, alcohol, nicotine, some antidepressants, and anti-cholesterol drugs – these can deplete or raise cortisol levels, creating an imbalance that affects sleep.
Are hormone imbalances causing your sleep problems?
Since we know that hormone imbalances can cause sleep problems, it's safe to say they could be the cause of your sleepless nights. However, it would be best to have blood tests for a definitive answer. Blood tests will reveal melatonin, cortisol, and serotonin irregularities, helping you figure out what's happening in your body.
If you found this article helpful, read our article covering the most common sleep disorders and see if any match your own experiences.