Sleep benefits body and mind in unexpected ways. Whether you are an athlete or a physicist, a good night’s sleep ups your game.
By Dona Suri
If you google “famous person needed hours sleep” you will get a dozen or more sites telling you “Margaret Thatcher slept for only four fours …” “Nicolas Tesla two hours…”, “Adolf Hitler three hours…” It’s a long list and the writers make it sound like staying awake day and night is some mark of genius.
And how does medical science react to that? Doctors say Phooey !
A good night’s sleep is essential. If you are a genius, a good night’s sleep will make you even more brilliant … and healthier too.
Both mind and body are recharging when you sleep. Sleep keeps hormone levels in balance and body processes moving smoothly. With sufficient sleep, all those connections in your brain get a chance to smooth the kinks out. You wake up feeling fresh, with a clear, alert and agile mind. Your memory is sharp, your mental uptake is quick, your judgment is keen, your reflexes are nimble, your mood is upbeat and your stress has dissipated.
Conversely, when you don’t get enough sleep you are letting yourself in for poor focus, reduced cognition, delayed reactions, mood swings, and a higher risk for illness, including obesity, Type 2 diabetes, high blood pressure, heart disease, stroke and poor mental health.
When sleep deprivation becomes a regular feature of a person’s life they build up a tolerance for it. Their brains and bodies are struggling but they are past the point where they can even realize what lack of sleep is doing to them. Inadequate sleep feels “normal” and prevents them from becoming aware of their own deficiencies.
If you are between the ages of 18 and 60, you should be getting seven hours of sleep every night. Children need more sleep. People who are 60-plus also need 7 to 9 hours each night. It’s a fact that older people tend to go to sleep earlier and get up earlier than they did when they were younger. In the case of oldies, the focus should be on getting enough deep sleep because that’s when tissue growth and repair take place, hormones are released, and cellular energy is restored. REM sleep is vital for memory, learning, and processing emotions.
Young or old, sleep is not an “off” button. Not at cellular level anyway. Lots of things — electrophysiological, neurochemical and genetic — are going on while you are asleep.
For instance, the body makes use of your sleep-time to clear debris from the lymphatic system. And protein is being synthesized way down deep inside the cells of the body while you are sleeping.
When you read “Human Growth Hormone” you may think it’s something that kicks in during childhood. That it does, but it keeps on kicking in, even when you are an adult. Your body is repairing itself all the time and for this, HGH remains essential, lifelong. Some HGH is released when you exercise, but much more – about 75 percent – flows into the bloodstream during deep sleep.
If you are a weight-watcher, you have another reason to aim for a good night’s sleep. You have two hormones that regulate hunger and appetite:
Leptin suppresses appetite and encourages the body to expend energy.
Ghrelin triggers feelings of hunger.
When you are sleep deprived, your body alters the hormones: leptin goes down and ghrelin goes up. Reduced glucose tolerance and impaired insulin sensitivity are two other consequences of sleep deprivation. It also triggers the brain’s endocannabinoid (eCB) system (the same area activated by marijuana). You crave fatty, sugary, salty food. Yes! It’s the munchies.
Now, brace yourself for something really amazing.
This is what researchers at Boston University found out: When you enter deep sleep, your neurons go quiet, blood flows out of your head and rhythmic, pulsing waves of a watery liquid called cerebrospinal fluid (CSF) flows in. This is the “slow wave”. It flushes toxic, memory-impairing proteins out of the brain. You could say that you are being “brain-washed”. The brains of people who are developing dementia experience fewer and fewer slow waves. Toxic proteins build up and memory declines.
The report that describes this research, Coupled electrophysiological, hemodynamic, and cerebrospinal fluid oscillations in human sleep, was originally published in Science, Nov 1, 2019.
Here’s the link: https://www.science.org/doi/10.1126/science.aax5440 .
Can’t help but remember Shakespeare. He may not have had precise medical knowledge but his intuition was solid: Way back in the 16th century he wrote: “Sleep knits up the raveled sleeve of care.”
Someone asks, “Do you know what sleep is?”
If you are NOT a neuroscientist, you say yes. You personally sleep for seven to eight hours every night … about a third of your life … and when you have been asleep, you know it.
If you ARE a neuroscientist, you say hmmmm… and pause to weigh up work of dozens of researchers. You think about all those neurotransmitters acting on different groups of neurons in the brain. And there’s that business with adenosine. (Adenosine is a chemical produced in the body; it’s job is to be a distress signal and modulate tissue repair.)
A neuroscientist cannot give you a scientifically acceptable, exact definition of all the processes and functions of sleep because he or she is still figuring it out.
He / she can tell you about adenosine. It builds up during waking hours, the more of it we have in our blood, the drowsier we feel. As soon as we are asleep, our cells start breaking down adenosine. In other words, the body performs an adenosine reset.
Neuroscientists are getting more knowledgeable about what goes on in the sleeping brain. The neurons that control sleep are the very same neurons that closely interact with the immune system. Anyone who has ever had the flu knows that it makes you drowsy. Cytokines are potent sleep-inducing chemicals that our immune system makes while fighting infections.
Theory: the body mobilizes cytokines in order to be able to redirect energy and other resources to the immune system as it beats off an invading virus.
Neuroscientists have pretty much figured out how our internal body clock works and its involvement in the sleep cycle. It operates on a 24-hour cycle known as circadian rhythm. You wake up feeling fresh but become increasingly tired throughout the day. (Adenosine is building up.) Fatigue peaks in the evening. You sleep. (Adenosine is broken down.) In seven or eight hours you will wake up feeling fresh again. This is sleep-wake homeostasis.
What and where is this body clock?
Welcome to the hypothalamus, conveniently located right on top of the brain stem. [Here comes a great word: supra means “above”, chiasm means “shaped like an X”.] Here we see two optic nerves meeting and forming an X. Just above this X is a cluster of cells called the suprachiasmatic nucleus. They read light signals and are the central pacemaker of the circadian timing system. Voilà ! Your internal clock!
As light fades, the suprachiasmatic nucleus signals the pineal gland to release melatonin, the sleep hormone. When the sun comes up, suprachiasmatic nucleus signals the hypothalamo-pituitary-adrenal axis which directs the adrenal gland to release cortisol, the wake up hormone.
When your sleep pattern is disrupted, your adenosine has failed to suppress your cortisol. It remains high, blocking melatonin release. You can’t fall asleep.
Sleep still has many secrets to puzzle out but what can be said for sure is that, in humans at least, sleep is essential for survival and prolonged sleep deprivation leads to severe physical impairment, followed by loss of consciousness, and eventually death.
The Snooze Cues listed above can help those who have trouble sleeping. Weighted blankets, posture pillows and mattresses, soothing sounds and nightlights are all sleep-inducing. And sometimes, just a glass of warm milk is enough to bring on the sandman.
Sleeping pills ? Only as a last resort.