The human body is a complex machine that needs oxygen, water, food and sleep to stay alive. There is no magic number for how many hours an adult should sleep, however it is generally thought to be around 8 hours. We think of sleep as a time to rest, but sleep is actually a time when our bodies are busy at work repairing and recharging.
What Happens During Sleep
The brain is busy cleaning house, getting rid of toxic waste from the brain cells used during the day, and creating new memories for the future. It also determines what is useful and important and stores it for future use. Your brain is also in control of many body functions during sleep such as breathing.
Lying down helps the kidneys do their best filtering and purifying of the blood. Kidneys therefore work the hardest at night. (Unless you work a night shift!)
Muscles including the heart relax, and blood flow to them increase. Heart rate slows down lowering blood pressure and that helps to heal and repair the heart and blood vessels. People who sleep seven to eight hours a night have the lowest rates of heart disease.
Certain hormones are released at night; the human growth hormone, important for children and teens, is one. Adrenalin release diminishes, making you feel more rested.
It normally starts dropping in the evening and continues through the night. With a lower body temperature the body releases melatonin to keep you sleepy.
If You Don’t Get a Good Night’s Sleep
Safety / Risk of injury
A good night’s sleep keeps you safer. Studies show you are more likely to trip, fall down the stairs, or have a car accident if you don’t get enough sleep.
The levels of ghrelin, an appetite-stimulating hormone has been found to be increased after poor sleep. Because the level is increased, the body thinks it’s hungry and needs more calories. And lack of sleep can just raise the sensation of hunger.
Not enough sleep can disturb the ability of the immune system to fight infection, leaving the body vulnerable to viruses that cause colds and flu.
One’s mood is almost always positive after a good night’s sleep. Depression can occur if there is a lack of sleep. Sleeping well means more to our overall well-being than simply avoiding irritability.
Some interesting facts about sleep
- About 1/3 of your life is spent sleeping. That means if you live to 75 years, you sleep for 25 years of your life sleeping!
- Humans can survive longer without food than they can without sleep.
- In the mammal world, a giraffe sleeps the least amount of time – 1.9 hours per day and the brown bat sleeps the most – almost 20 hours per day.
- A cat sleeps for 2/3 of its life.
- Sleeping less than 6-7 hours each night will shorten your life span.
- One in 20 adults unconsciously grinds their teeth at night.
- You can’t sneeze in your sleep.