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The Relationship Between Hormones And Sleep


Some hormones are known to make us feel tired, help us relax and fall asleep; whereas the others depend on the quality and length of our sleep. Hormone levels rise and drop throughout the day and this fluctuation is usually directly or indirectly related to our circadian rhythm (biological clock). Hormones ensure we have more energy in some parts of the day and less in others; they let us know we are hungry, full, or sleepy. A disruption in sleep time and quality can negatively reflect on hormones in our body. They, not being able to fulfill their role, can further trigger problems related not only to sleep; but also our diet, energy levels, mood, concentration, libido, immune system, and menstrual cycle in women.

Hormones and the endocrine system

When we talk about the endocrine system, we usually think about a number of glands which secrete certain hormones. Each hormone has its own role (or numerous roles) – it tells a cell to do or stop doing something (for example, insulin orders a muscle cell to consume sugar from blood), it tells an organ to do or stop doing something (in extremely stressful situations, cortisol can get ovaries to shut down), or it lets us know certain information (ghrelin tells us we are hungry, whereas leptin informs us we’ve had enough food).

Figure 1: The Endocrine System

Endocrine glands are controlled by the hypothalamus – a small part of the brain which is also involved in the regulation of the nervous system and circadian rhythm. It is one of the components of the ‘flip-flop switch’ – a mechanism which works to get us to fall asleep and wake up.

Hypothalamus produces several hormones which tell the pituitary gland to start secreting its hormones. They will further get their message going. The pituitary gland is known as the ‘master gland’ of our endocrine system because it tells other glands what to do. It also produces important hormones, like the growth hormone, which is mainly released during slow-wave sleep; or luteinizing hormone, which controls estrogen and testosterone.

Adrenal glands produce stress hormones such as adrenaline and cortisol. They affect metabolism and blood pressure, they also help the body respond to stress.

These three are known as the hypothalamic–pituitary–adrenal (HPA) axis. A disruption to the HPA axis may result in an inability to fall asleep, developing narcolepsy or metabolic problems.

The thyroid gland produces thyroid hormone which mainly regulates metabolism. It affects each cell of the body as they all have their own energy consumption – their own metabolism.

The pancreas is related to digestion of food and produces insulin and glucagon, hormones that keep your blood sugar balanced. Ovaries in females make estrogen and progesterone. These hormones ensure getting feminine characteristics in puberty, going through menstrual cycles and pregnancy. They also have a role in mood and good sleep in men and women.

Testes in males produce testosterone. Testosterone is responsible for giving men strength, facial hair and plays a role in reproduction. Testosterone is also linked to mood and sound sleep in men and women.

With age, everyone naturally loses the hormonal volume, as endocrine glands slow down due to slow metabolism. However, there are many behavioral and health factors which affect endocrine glands and hormones. Poor diet, sedentary lifestyle, sleep deprivation, and stress lead to hormonal changes. Hormonal changes may further lead to weight increase, sleep and mood problems.

Circadian rhythm and hormones

Circadian rhythm in humans depends on the daytime and nighttime – and guides our body processes accordingly. However, there are individual differences among people; such as when we prefer to get up, have a meal, be productive, etc. These differences are known as chronotypes. Regardless of your chronotype, one thing all people have in common is that they are most active during the day and sleep at night. Here are examples of how some hormones fluctuate throughout the day. Note that not all hormones are strictly linked to our circadian rhythm.

Melatonin, for example, is the lowest in the morning – this is when we feel the most refreshed and energetic. It slowly increases during the day, though almost unnoticeably. Melatonin increases sharply after 8 pm and reaches its highest point at about 4 am, after which it plummets back to normal daily levels.

Cortisol, the stress hormone, is low at night. That is because our body is relaxed during sleep. If we get too stressed and our adrenal glands produce too much of stress hormones, we might be unable to fall asleep. Cortisol peaks at about 7-8 AM – the time when we are supposed to wake up.

Which hormones are released while we sleep?

Many hormones are secreted while we sleep. They are essential for the feeling of refreshment we have when we wake up. Not only that, but they are important for the proper function of all the organs and cells in our body. Here are the hormones which are released in high amounts during sleep:

  • Growth hormone. In children, this hormone helps their growth, but in adults, its primary purpose is restoring and ‘rejuvenating’ tissue and cells.
  • Oxytocin is linked to the feelings of love, sexual behavior, and bonding between a mother and a child.
  • ADH (Antidiuretic hormone) slows down the function of kidneys so that the need for going to the bathroom at night is reduced to the minimum.
  • Prolactin is mainly associated with producing milk in women who have babies, but it also exists in men and women who don’t have children. Prolactin has a reproductive role and regulates the immune system and metabolism.
  • Thyroid-stimulating hormone peaks between 1 and 2 am. Being of huge importance for our metabolism, it is not surprising that poor sleep affects metabolism.
  • Ghrelin and leptin regulate the feelings of hunger and fullness.

Stress hormones should be in the low while we sleep, as well as insulin and adiponectin (blood sugar regulators). A good night’s sleep ensures all hormones peak at the right time. It brings a stable circadian rhythm and healthy mind and body.

sleep hormones visualized
Figure 2 Circadian rhythm and hormones. Time-of-day at which circulating levels of key endocrine factors peak in humans. Abbreviations utilized include: GH, growth hormone; TSH, thyroid stimulating hormone; PRL, prolactin; T3, triiodothyronine; RAAS, renin-angiotensin-aldosterone system; FGF21, fibroblast growth factor 21; (F), females only; (M), males only. Taken from: Circadian Clock Control of Endocrine Factors. Nature reviews. Endocrinology.

Why are hormones important?

Hormones usually depend on each other and a health or behavior problem that causes a change in one hormone can further lead to a health problem that causes another hormonal change so that a person may end up treating a hormone imbalance instead of the underlying cause or causes.

Hormones are important for our mood, thinking, sleeping, metabolism, immune system, and physical abilities. It may come as a surprise that, for example, both estrogen and testosterone regulate all of the above-enumerated things. Many other hormones take part in these as well – for example, metabolism is also regulated by thyroid hormones, and prolactin, melatonin, and insulin. This means that hormones have a lot more than one role – some of their roles haven’t been discovered yet, and some are still unclear. Almost all aspects of our daily life functioning are linked to our hormones. This is why we have to take special care to maintain a healthy diet, good sleep hygiene, be physically active, and ditch alcohol and tobacco in order to let our hormones do their part.

Sleep disturbances and hormonal changes

Sleep problems can cause hormonal imbalances, and in turn, hormonal imbalances can aggravate sleep problems.

It is known that sleep deprivation, even for a short time, has noticeable consequences on our hormones. In healthy young people, it can significantly decrease testosterone in men and estrogen in women. It increases insulin and causes higher insulin resistance. A lack of human growth hormone leads to skin and immunity problems. If disturbed, many hormones change our mood so we become more prone to stress and anxiety, along with insomnia.

Ghrelin causes you to have late night meals and eat more during the day – this might be a body’s way to get more energy which is lost due to not sleeping. If the thyroid doesn’t work properly, adrenal glands start producing more adrenalin to compensate, but this hormone also keeps us awake.

Many sleep problems which include short sleep time or poor sleep quality go hand-in-hand with hormonal imbalances.

Circadian rhythm disorders and bad sleep schedule confuse our body and the result is bad circadian hormone management. This means our melatonin could surge at inappropriate times, making us sleepy. High cortisol and adrenalin presence at sleep time can completely ruin our sleep time plan, leaving us tired the following day.

Change your sleep habits in order to have healthy hormone levels

If you think you frequently suffer from non-restorative sleep, you might need to change your sleep habits significantly. Here are some of the most important rules when it comes to healthy sleep.

  • Go to bed and wake up at about the same time every day (including the weekends). This way, your body will be able to program the internal clock according to your day. Even if you go to bed late one time, make sure to wake up early, as per schedule. You will make up for that loss in the following nights. It’s important to stick to your rhythm, and the hormones will follow.
  • Do exercises daily (but not just before bedtime). They help your body to get in shape and your endocrine glands to work properly. After all, a sedentary lifestyle is associated with a lack of estrogen in women and insufficient testosterone in men; not to mention insulin (and insulin resistance). Physical inactivity lessens your chances of getting a good night’s sleep.
  • Make a bedtime routine, including a warm shower before bed (it gets you to fall asleep easily and increases your deep sleep – the stage in which your growth hormone peaks).
  • Turn off technology – blue light from screens postpones melatonin production and increases the time you need to fall asleep.
  • Avoid alcohol and caffeine. Alcohol can make you fall asleep easily, but it prevents you from getting into the deep sleep, whereas caffeine in food and drinks keeps you awake for a long time.
  • Sleep in a dark room. Those who leave a light on are proven to have high levels of insulin at night. This can lead to insulin resistance and further problems associated with it in the future if such sleep habits continue.

Additional resources

  1. The Endocrine System. RN. https://www.rn.com/clinical-insights/endocrine-system/ Accessed January 6, 2019.
  2. Hirotsu C, Tufik S, Andersen M.L. Interactions between sleep, stress, and metabolism: From physiological to pathological conditions. Sleep Science. November 2015. https://www.sciencedirect.com/science/article/pii/S1984006315000607 Accessed January 9, 2019.
  3. Gamble K. L, Berry R, et al. Circadian Clock Control of Endocrine Factors. Nature reviews. Endocrinology. May 27, 2014. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4304769/ Accessed January 9, 2019.
  4. Good Night, Sleep Tight. Women’s International Pharmacy. https://www.womensinternational.com/portfolio-items/sleep/ Accessed January 9, 2019.

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