Human beings sleep for approximately one-third of their lifetime, but the endogenous mechanisms underlying sleep and its role in homeostasis remain to be fully elucidated.
Sleep is important for plenty of reasons. Sleep impacts our hormones and hormone levels impact our sleep. Both too much and not enough time under the covers can influence hormones. That is why a good night’s sleep is essential to keeping good health and hormonal levels balanced.
Hormones are chemical messengers that play a vital role in regulating the body processes, systems and functions. The body needs a range of different hormones to function properly. They are released through the endocrine system, a network of organs and glands located throughout the body. They are responsible for many body functions, including:
- Metabolism and appetite
- Body temperature
- Sexual function, drive and reproduction
- Heart rate regulation
- Blood pressure regulation
- Sleep-wake cycles
Various hormone functions and their release are impacted by sleep or circadian rhythm. Getting adequate sleep is important for regulating a number of hormones including cortisol, estrogen, progesterone, insulin, melatonin, thyroid hormones and growth hormone (HGH).
Melatonin controls sleep patterns and tells our body when to get to sleep. Human growth hormone is released during deep sleep hours, which is vital to cell growth and repair. Other hormones, like cortisol, depend on sleep timing, duration and quality for their release. Nearly every hormone in the body is released in response to your circadian rhythm, also known as the sleep-wake cycle.
Cortisol levels rise rapidly in the middle of the biological night and peaks during the biological morning. This hormone is released in a pulsatile manner through the 24 hours. It is produced by the adrenal glands and it’s also known as the stress hormone. Cortisol helps regulate other hormones in the body.
Poor sleep can have a number of negative effects on cortisol release. The recommendation of some experts is sleeping 7 to 9 hours every night to keep your cortisol levels in check.
Growth hormone levels are increased during sleep and peak immediately subsequent to sleep onset. It is also known as somatotropin and it plays a vital role in protein synthesis, muscle development, metabolism and immunity. Poor sleep quality or reduced sleep hours reduces the level of growth hormone and you may be less able to repair injuries and more likely to accumulate fat tissue.
According to a 2016 study, growth hormones affect the regulation and metabolism of glucose, lipids and proteins in the body. Furthermore, HGH deficiency has been shown to be associated with alterations in growth, body composition and metabolism.
Another important hormone is melatonin, which exhibits robust circadian rhythmicity. Studies using constant routine and forced desynchrony protocols demonstrate that melatonin levels are high during the biological night versus day. It is produced by the pineal gland that is associated with the body’s sleep-wake cycle. Disrupted or poor sleep can have impacts on melatonin and its role in promoting sleep in the brain.
Experts say that melatonin controls more than 500 genes in the body including the genes involved in the immune system, so managing your melatonin with good sleep is key.
Sleep disruption or poor sleep can directly affect the production and levels of hunger hormones in the body. This can disturb hunger, appetite and food intake, potentially leading to weight gain. Poor quality sleep disrupts leptin, ghrelin and insulin levels, which are responsible for fullness, hunger, blood sugar regulation and fat storage. Ghrelin levels increase prior to habitual meal times and decrease thereafter.
The ideal amount of sleep required for most adults is around 7 to 9 hours and if you think that after accumulating sleep debt during the week, you can catch up sufficiently on the weekends, according to research, you’re wrong.
Missing sleep can lead to reduced immunity, more frequent infections, spikes in appetite, higher calorie consumption and weight gain. On the contrary, too much sleep (more than 9 hours) has been shown to cause an increase in daytime fatigue, reduced metabolism, impaired focus and disrupted sleep cycles.
Like everything in life, it is important to maintain a good balance. Both one end of the scale and the other are bad. Too little and too much sleep can cause negative effects on our health and according to different studies it is tightly related to a hormonal imbalance.
Kim TW, Jeong JH, Hong SC. The impact of sleep and circadian disturbance on hormones and metabolism. Int J Endocrinol. 2015;2015:591729. doi:10.1155/2015/591729