Sleep Update – Scientific Highlights
G’day, Dr Karl here.
There are a lot of people who live there who want to have fun now and sleep when they are dead. But no, not a good plan. You’d better get seven to nine hours of regular sleep every night so that you can live longer and better.
So let’s update our Sleep Knowledge database. How about starting with how much sleep we really need. It varies a bit. But once you start getting less than six hours of sleep at night, you’re much more likely to get various cancers, Alzheimer’s, diabetes, and fat.
Too little sleep can weigh you down in a number of ways.
Looking at hormones, not getting enough sleep will simultaneously raise blood levels of a hormone that makes you hungry while suppressing another hormone that makes you feel full. Then looking at the brain, the regions related to impulse control are turned off or even turned off. To make matters worse, at the same time, the activity of your tonsil (another part of your brain) is swollen (the amygdala causes pleasure-seeking behavior, and this includes eating fatty foods). In summary, people who are sleep deprived will choose foods that increase their energy intake by up to around 50%.
But what if you deliberately eat less to lose weight, while still being deprived of sleep? Very annoying, your metabolism will hang on to its fat stores and for energy it will break down your muscles instead. In fact, about 60% of this weight loss (when not getting enough sleep) comes from the loss of muscle mass.
Sleep deprivation also affects children. Now your average three-year-old sleeps about 12 hours a night. But what about the three-year-old who sleeps ten and a half hours or less every night? Compared to a child who sleeps 12 hours a night, short sleepers have a 45% increased risk of being obese by the time they reach the age of seven.
Today, a global sleep study is accidentally conducted on more than 1.5 billion people on 70 continents each year. We call it Daylight Saving. In the spring, when we switch to summer time, the day is only 23 hours long, so we lose a whole hour of sleep. The next day, there is a 24% increase in heart attacks worldwide.
Insufficient sleep also affects male sex hormones. One study looked at healthy young men who slept four hours a night for four nights. They ended up with the testosterone levels of a man around 10 years old. In other words, in terms of hormonal virility, a few consecutive nights of insufficient sleep will make a man about ten years old. Similar changes in women’s reproductive health and hormonal profiles occur in young women who don’t get enough sleep.
What about lack of sleep affecting a vaccine injection? Well, if you don’t get enough sleep in the week before your annual flu shot, your immune system will produce less than 50% of its regular antibody response – and your vaccine will be much less effective. In another way related to the immune system, if you consistently sleep less than seven hours a night, you are three times more likely to be infected with a cold from a rhinovirus.
In addition to interfering with your body weight and immune system, insufficient sleep is found to be one of the most important lifestyle factors associated with Alzheimer’s disease. For some time now, we’ve known that people who get six hours of sleep or less per night, or those with sleep apnea or insomnia, are at a higher risk for Alzheimer’s disease.
First, a bit of contextualization. In Alzheimer’s disease, a sticky toxic protein called beta-amyloid builds up inside the brain. Fortunately, deep sleep activates a massive flushing of dangerous metabolic chemicals through what is known as the “glymphatic system”. Either missing the full 7-9 hours of sleep, or even a lack of deep sleep in the early hours of the night, leads to a sudden jump in beta-amyloid – in the blood, cerebrospinal fluid, and in the brain. . .
Now this is where evolution has been very nasty to us. This beta-amyloid chemical builds up in those very regions of the brain that generate deep sleep! You can see that this is a very nasty positive feedback loop – less deep sleep leads to more amyloid, which leads to even shallower sleep, which leads to even more amyloid and it keeps repeating itself.
Interestingly, Margaret Thatcher and Ronald Reagan both felt that sleeping time was a waste of time and that they both contracted Alzheimer’s disease.
But the good news is that treating sleep disorders in middle-aged and older adults can delay the onset of Alzheimer’s disease by up to 10 years.
So, if there is a golden rule in life, it’s to get enough sleep.