See also: circadian rhythms
Benefits of Sleep
During sleep, our bodies secrete hormones that help to control appetite, energy metabolism, and glucose processing. Obtaining too little sleep upsets the balance of these and other hormones. For example, poor sleep leads to an increase in the production of cortisol, often referred to as the “stress hormone.” Poor sleep is also associated with increases in the secretion of insulin following a meal. Insulin is a hormone that regulates glucose processing and promotes fat storage; higher levels of insulin are associated with weight gain, a risk factor for diabetes.
Insufficient sleep is also associated with lower levels of leptin, a hormone that alerts the brain that it has enough food, as well as higher levels of ghrelin, a biochemical that stimulates appetite. As a result, poor sleep may result in food cravings even after we have eaten an adequate number of calories. We may also be more likely to eat foods such as sweets that satisfy the craving for a quick energy boost. In addition, insufficient sleep may leave us too tired to burn off these extra calories with exercise.1
Studies have found that a single night of inadequate sleep in people who have existing hypertension can cause elevated blood pressure throughout the following day. This effect may begin to explain the correlation between poor sleep and cardiovascular disease and stroke. For example, one study found that sleeping too little (less than six hours) or too much (more than nine hours) increased the risk of coronary heart disease in women.1
Sleeping more flushes junk out of the brain
Sleep is something like a soft reboot. We knew that slow brainwaves had something to do with restful sleep; researchers at the Washington University School of Medicine in St. Louis have now found out why. When we are awake, our neurons require energy to fuel complex tasks such as problem-solving and committing things to memory. The problem is that debris gets left behind after they consume these nutrients. As we sleep, neurons use these rhythmic waves to help move cerebrospinal fluid through brain tissue, carrying out metabolic waste in the process.
In other words, neurons need to take out the trash so it doesn’t accumulate and potentially contribute to neurodegenerative diseases. “Neurons serve as master organizers for brain clearance,” the WUSTL research team said in a study recently published in Nature. 1
Counterpoint
🔗 Footnotes
- Sleep restriction increases the drive to eat, and excess food intake resulting from not sleeping enough is more related to cognitive control and reward mechanisms than to appetite hormones.2
Radical ideas, unproven experiments
- Why I stop sleeping on beds and went to the floor instead
- Digital devices decreasing our experience of boredom, harming our sleep
- Boredom as a helpful condition for sleep