Doctors are commonly heard advising patients to rest – perhaps after flu or even surgery. You may even remember how drained you feel while you’re ill.
This is because your immune system prompts your body to sleep in order to gain the healing benefits. But not only does sleep have restorative qualities, it also supports your natural protection.
We have a defence system of “natural killer cells” (NK cells) in our bodies. These cells are best known for killing virally infected cells and protecting us from disease. They are also know for their ability to kill tumour cells and are particularly useful in the early stages of fighting cancer.
A recent study was designed to monitor how sleep affects the number of NK cells in the immune system. The study was done over two separate nights on a group of young, healthy men. On the first night, the men were allowed a full 8 hours of sleep and on the second night, they had only 4 hours of sleep. The results showed a 70% decrease in NK cells on the morning after the sleep deprivation compared to after the night of full sleep.
Another recent study involved participants being deliberately subjected to the cold virus. Those who slept for an average of 5 hours each night were found to have a 50% infection rate. Those sleeping for 7 or more hours had only an 18% infection rate.
Stress and anxiety are also factors in this debate as they produce cortisol (our stress hormone) that is known to suppress some aspects of the immune system. Working long hours or living in a difficult home environment are likely to result in both less sleep and more cortisol. And so the argument goes round in circles until a regular routine of healthy sleep can be achieved.