Human beings need sleep to survive. And while there is no record of a human dying from sleep deprivation, animal research strongly suggests it could happen. The seemingly simple act of slumber actually involves a complex choreography of biochemical and physiological processes that keep us functioning.
While you sleep
At bedtime, your cortisol hormone level dips significantly (it slowly increases through the night so you are alert come morning). Your heart rate and breathing slow. As you sleep, your blood pressure plunges, and your body temperature drops. You pump out growth hormones and regulate your hunger hormones. And your brain cleans house.
You are not in a deep sleep most of the night. You cycle through stages all night long, even waking for a second before each cycle begins again. You probably don’t even realize you wake up. While your body rests during sleep, your brain remains active controlling body functions — like breathing — even as it rejuvenates.
There are two sleep states — rapid eye movement, or REM, where dreams occur, and non–rapid eye movement, or NREM. REM sleep is active sleep. You dream, your breathing and heart rate increase and become irregular, your muscles relax and your eyes flutter. NREM sleep has four stages, going from drowsiness to deep sleep. The restorative effects of sleep occur during deep NREM sleep. Yet, even during deep NREM sleep, your mind is processing information.
Benefits of sleep
When you sleep, your brain recharges, your cells repair themselves and your body releases important hormones that heal and rejuvenate. A restful night’s sleep helps keep your brain sharp, your immune system strong, your waistline trim and your skin healthy. It also lowers your risk for depression, diabetes, obesity, high blood pressure and heart disease.
While sleep won’t actually help you shed unwanted pounds, regular restful nights can prevent weight gain. How, you wonder? Insufficient sleep increases secretion of a hormone called ghrelin, which signals hunger. Along with this, there is a decrease in the hormone leptin, which transmits the feeling of fullness. And the lack of sleep may actually diminish your capacity to fight the urge for junk food — because that is just what your body will crave.
Getting enough quality sleep protects your mental health, physical health, quality of life and safety. Sleep helps keep you happy, which in turn bolsters all your relationships. It can prevent headaches. It lowers your risk of a car crash. A good night’s sleep even raises your pain threshold. Quality sleep time is essential for your good health. Perhaps that’s why it’s called "golden slumber."