Hormones and sleep
Hormones are chemical messengers that travel in the bloodstream and trigger certain bodily functions. Several hormones are associated with our circadian rhythm and regulating the sleep/wake cycle.
The levels of certain hormones in the body fluctuate throughout the day in response to our circadian rhythm, telling us, for instance, when to feel sleepy and when to wake up. Although some hormones directly regulate sleep, the relationship between hormones and sleep is a two-way street: the production of hormones, and the impact this has on sleep patterns, can also be influenced by the quality and quantity of our sleep.
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HORMONES OF THE SLEEP/WAKE CYCLE
Melatonin
Pineal gland
The “sleepiness” hormone helps build our sleep pressure and decrease body temperature, both necessary for us to be able to fall asleep and stay asleep.
Progesterone
Ovaries and adrenal gland
Progesterone affects body temperature, REM sleep, and levels of gamma-aminobutyric acid—which can induce relaxation and sleepiness.
Human growth hormone
Pituitary gland
This hormone is released in pulses during deep sleep. It plays a vital role in muscle and tissue repair and metabolism.
Oxytocin
Hypothalamus and pituitary gland
The “love” hormone is important for social and sexual behavior and slows the nervous system to promote sleep.
Cortisol
Adrenal gland
The “stress” hormone increases alertness, so it peaks in the early morning. It is also triggered as part of the body’s “fight-or-flight” stress response to threatening situations.
Serotonin
Pineal gland and the gut
The “happy” hormone’s main job is to regulate mood and maintain wakefulness, but serotonin is also turned into melatonin, which is vital for inducing sleep.
Aldosterone
Outer adrenal glands
This hormone acts to regulate sodium and potassium in the blood. High levels secreted during sleep help prevent you from needing to urinate at night.
OTHER HORMONES AFFECTED BY SLEEP
Prolactin
Pituitary gland
Hormone involved in the immune response, along with the production of breast milk. Most prolactin is secreted during deep sleep, so good sleep ensures successful release.
Testosterone
Testes
Made in the testes, ovaries, and adrenal glands, testosterone affects libido and fertility. Release peaks during sleep, so good shut-eye is key to sexual and reproductive health.
Insulin
Pancreas
This hormone regulates blood sugar levels. Some of this vital process takes place in deep sleep, so sleeping well helps keep blood sugar levels in a healthy range.
Adrenaline
Adrenal glands
Hormone produced as part of the body’s stress response. Raised levels of adrenaline can block the ability to fall asleep, so avoiding too much stress before bedtime is key for sleep quality.
Ghrelin and leptin
Fat tissue and stomach
Leptin is produced in the fat tissues, and ghrelin in the stomach. These hormones control hunger and fullness, and good sleep keeps them well-balanced.