When we fall ill, we are always advised to sleep, get a good night’s rest, and stay at home – if possible, stay in bed. This might not be all too difficult: after all, we often feel weak when we are ill; and we often do want to sleep when we have infections, such as typhoid fever or the flu.
What is the reason for this ever-reliable exhortation of “Sleep and rest?” And why do we feel sleepy when we are sick? Is there a link between sleep and the immune system?
Before you can establish a connection between rest and recuperation, you have to know how the immune system works. When your body picks up a pathogen, such as a virus or a bacterium, your body sends out cells to recognize it. Once these cells find out what the invader is your body launches a defense response to kill the infection. This would entail you having to endure a fever, body pains, sometimes even vomiting or loose bowel movement as your immune system puts up a fight. If you get well, your immune system can create memory cells, which will protect you from future infections.
One such molecule that promotes destruction of invaders is called interleukin-1, or IL-1. IL-1 encourages special blood cells called B lymphocytes to produce antibodies, which lead to viral destruction. IL-1 also allows T lymphocytes, another type of immune system cell, to attack bacteria.
IL-1, by the way, is produced at its greatest in the presence of a protein called di-muramyl peptide. This peptide, in turn, is produced by bacteria in the body, especially when you are sleep-deprived. That is, if you do not sleep, you become more susceptible to sickness, which stimulates your immune system, which, thanks to the sedative effects of IL-1, makes you sleepy.
In other words, the immune system works to make you sleep; and sleep allows your immune system to work.
All this, researchers found by studying laboratory animals, as well as people in experiencing Rapid Eye Movement (REM) sleep, loosely defined as “deep sleep.” It is non-REM sleep that stimulates the immune system, but researchers found that to keep at the top of the game, humans must have as much REM sleep as possible.
Now why is this so? Studies have found that REM sleep allows a complete “battery recharge” in the body, allowing memories to become permanent in the brain, and allowing the immune system to repair any damages done to cells and organs.
This is most evident if you have experienced deep sleep: you wake up with a sense of clarity, and feel rested. REM does more than memory plastering: one minute of REM is equal to five of non-REM sleep, so that sometimes, you can feel rested after a good nap, but still feel fatigued despite having shallow sleep all night.
What other benefits does sleep carry?
- If you are a teenager and still going through your growth phase, then you need a lot of sleep. This is because the pituitary gland churns out growth hormones during sleep; leave off those few hours in dreamland, and you could put your height behind you.
- As evidenced by cranky co-workers, sleep keeps you on your toes and still keeps a smile upon your face. Studies show that people who sleep at least seven hours a night not only perform better at work, but feel better about themselves and consequently are less hostile to their co-workers.
- Recent research has also shown that people who do not experience frequent REM sleep, or those who do not sleep more than seven hours a night, have impaired motor functions and balance. You may notice this after pulling an all-nighter: you have a hard time walking straight, and you may sometimes be clumsy.
- Lack of sleep, on the whole, impairs memory, vision, and even the ability to make wise judgment.
- People who have less sleep are more likely to experience anxiety and depression, which, in turn, impair the immune system’s ability to heal illness.
In short, sleep may seem like a waste of a precious few hours, but if it means giving you a longer life, then you should have as much deep sleep as you possibly can. So get that immune system stimulated, have a few winks, and say hello to good health!