We already know that a lack of sleep will actually prevent your brain from being able to make new memories. You end up feeling as though you're amnesiac.
A lack of sleep will lead to an increased development of a protein in the brain connected with Alzheimer's disease because it is during deep sleep at night that a system within the brain starts to wash away this protein. So if you're not getting enough sleep each and every night, more of that Alzheimer's-related protein will build up. The more protein that builds up, the greater your risk of developing Alzheimer will be in later life.
What are the effects of the lack of sleep on the body? We know that a lack of sleep impacts your immune system(免疫系统).After just one night of four to five hours of sleep, there is a 70% reduction in immune cells called natural killer cells. And that's the reason that short sleep predicts your risk for developing many forms of cancer.
In fact, the link between a lack of sleep and cancer is now so strong that recently the World Health Organization decided to classify any form of nighttime shift work as a probable cause of cancer. It is during deep sleep at night that your heart rate drops, your blood pressure goes down. If you're not getting enough sleep, your blood pressure rises. If you're getting six hours of sleep or less, you'll have a 200%increased risk of having a deadly heart attack or stroke in your lifetime.
There is a global experiment that is performed on 1.6 billion people twice a year and it's called daylight savings time. And we know that in the spring, when we lose one hour of sleep, we see a 24% increase in heart attacks the following day.
Another question, perhaps, is what is the recycle rate of a human being? How long can we actually last without sleep before we start to see worsening in your brain function? And the answer seems to be about 16 hours of wakefulness. Once you get past 16 hours of being awake, that's when we start to see mental and physical damages in the body. We know that after you've been awake for 19 or 20 hours, your mental capacity(心智能力)is so damaged that you would be as slow as someone who was drunk. So if you were to ask me what is the recycle rate of a human being, it does seem to be about 16 hours and we need about eight hours of sleep to repair the damage of wakefulness.