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Popular culture constantly emphasizes the relationship between sleep and success, perfectly summed up in the familiar saying “Early to bed and early to rise makes a man healthy, wealthy and wise”. Admitting there’s some truth in this (and that the maxim applies to everyone regardless of gender) how does science explain it?

Sleep is a fascinating subject to science because it involves so many factors and mechanisms, from brain anatomy to neuronal activity and circadian rhythms. The beauty of it is that no matter how much knowledge we accumulate, there’s always something new to learn!

Hormone Balance

One of the most vital functions of sleep is that it helps reload our hormones, with a significant impact on our health and wellbeing. At the end of the day, it’s less about “recharging our batteries” – as we like to say every time we feel we need a rest – than about reloading our hormone levels.

In fact, sleep affects almost every type of tissue and system in the body – from the brain, heart, and lungs to metabolism, immune function and mood – and hormones kind of control all this, by sending “messages” to our cells and organs through the bloodstream, thereby controlling many of our body processes.

Hormones relate to sleep in a number of ways. They make us feel sleepy at night and alert in the morning. They boost our immune system, help us grow, make us hungry and influence our dreams. In fact, it’s a two-way relationship: hormones affect our sleep and sleep, in turn, affects hormone release and regulation.

Wake-up Call

Take Melatonin, for example, which you’re probably familiar with because it’s a popular sleep inducer, sold in pharmacies (in a synthetic form, though). Melatonin is a natural hormone produced by the body’s pineal gland, located just above the middle of the brain. During the day, the pineal gland is inactive. Once the lights go down, however, the pineal “wakes up” and starts producing melatonin (now you know why it’s also known as the “Dracula” of hormones). Melatonin is released into the blood, you feel calmer and less alert and, unless it’s Friday night and you have better plans, sleep comes naturally. While you sleep, melatonin levels stay elevated, until they fall back to low levels with daylight.

If Melatonin helps us falling into sleep, another hormone, cortisol, does just the opposite, functioning as an all-natural wake-up call. If you’re not too stressed, its levels naturally decrease at bedtime, increase during the night, and peak just before you wake up.

After a good night’s sleep in a perfect mattress, you will probably be feeling active, and energized. And hungry too, because cortisol sends a message to your brain that screams “I want to eat the world!” and because two hormones, released during sleep, (ghrelin and leptin) are programmed to balance our appetite. Ghrelin, for instance, stimulates hunger, and during sleep its levels are regulated, keeping us from feeling hungry. Consequently, poor sleep might create an urge to eat more.

Last but not least, sleep is essential for growth. This is why babies sleep so much and it’s so important for children to get good sleep. Adults too, produce the growth hormone, which in their case is crucial for tissue repair.

Pleasure and Pain

Ever wondered why some dreams feel so good? Well, maybe because we get to travel to faraway places for free, and we catch up with friends and loved ones whom we miss. But it might have something to do with hormones, as well, since while we snooze our body releases oxytocin, a.k.a the “love hormone”, which peaks after 5 hours of sleep.

Produced in the hypothalamus, oxytocin is involved in childbirth, breastfeeding and social behavior, creating stronger connections, and it may influence our dreams, making them really sweet. Conversely, cortisol, the “stress hormone” (which, by the way, also has more positive functions like keeping us awake and alert) can have a negative impact on our dreams. Here’s why reducing stress is so important, don’t let too much cortisol run in your veins!

Sleep also helps boost prolactin, which is involved in metabolism and immune system regulation. Sleep well to keep it in balance, unless you want to end up less resistant to diseases and with difficulty concentrating.

In the mood for sleep

Science sheds some light on the fascinating link between sex and sleep. Finally, we know the reason why men pass out within a few minutes after sex. Apparently, it has nothing to do with a sudden lack of interest.

The answer, again, is in the hormones our bodies release during intercourse. After climax, a cocktail of feel-good hormones and neurotransmitters like endorphins are released in your brain, putting you in the mood for sleep. During sex, increased levels of oxytocin make you feel super connected to your partner, and lower levels of cortisol make you feel calmer. The result: love and sleep like a log!

While it is scientifically proven that sex puts you in a pleasant, relaxing state that promotes sleep, it affects women and men differently. In women, increased estrogen levels will affect the REM cycle and result in a deeper sleep. Men, on the other hand, will produce more prolactin which is known for making you feel tired (by the way, levels of testosterone are higher during sleep).

Sex affects sleep, that’s for sure, and vice –versa, as studies show that for women at least, more sleep means better sex. A study published in The Journal of Sexual Medicine showed that greater sleep duration was related to greater sexual desire in women and a 14% increase in the likelihood of sexual activity the next day.
So basically, good sleep brings good sex. Now, that’s not a bad combination, is it?


About Editorialista

Madalena Galamba is a writer and journalist. She learned how to write in 1981 and hasn't stopped since. She studied journalism in Lisbon and cinema in New York. She spent some years of her youth in Paris, and even though she didn’t have to live in an attic, the experience left an indelible mark. She was the founder and editor of Blue Design magazine and wrote for the newspapers Expresso, Público and Fora de Série. In 2017, she founded Editorialista, a copywriting and content studio based in Lisbon. She meditates regularly and her favorite idiomatic expression is probably Oh la la.

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