We're always told we need to get our eight hours of sleep – but who decided that? Was it just plucked out of thin air?
According to Matthew Walker, author of book Why We Sleep, and Professor of Neuroscience and Psychology at the University of California, it's not just yawn-prevention that's the reason we're advised to get a full night's sleep.
It seems there are actually some serious bodily effects you didn't realise could occur as a result of lack of sleep, and it gives real reasoning to the advice to get eight hours a night. Walker spoke to Tech Insider to explain just what happens inside your body if you don't catch enough zeds:
If you've noticed yourself becoming forgetful, it might be worth thinking back to how much sleep you've had recently (if you can remember, that is). "We certainly know that a lack of sleep will actually prevent your brain from being able to initially make new memories," explains Matthew Walker in the Tech Insider video.
"It's almost as though without sleep the memory inbox of the brain shuts down and you can't commit new experiences to memory. You can't essentially make and create those new memories," the expert advises.
But it's not just your everyday memory that might suffer, Walker also points out a scientific connection between not getting enough sleep and the onset of Alzheimer's disease.
"A lack of sleep will lead to an increased development of a toxic protein in the brain that is called beta amyloid," explains the neuroscientist. Sleep usually washes away this protein, so the less sleep you get, the more will build up - and the higher your chances of developing Alzheimer's.
This is more an issue for men than for women. "Men who are sleeping just five to six hours a night have a level of testosterone which is that of someone 10 years their senior,' explains Matthew Walker.
What that means is that their quality of sperm won't be quite as good as it should be for a person of their age, hindering your chances of a successful conception.
3. Immune system
It's normally when you feel tired and run down that you get ill, we all know that. But this lethargy can also pave the way for more serious illnesses to bed in. "After just one night of four to five hours of sleep there is a 70% reduction in critical anti-cancer fighting immune cells called natural killer cells," the expert explains. Walker notes that lack of sleep is most likely to play a role in the development of bowel, prostate and breast cancers.
And this isn't just some loose theory, either. "The link between a lack of sleep and cancer is now so strong that recently the World Health Organisation decided to classify any form of night time shift work as a probable carcinogen," he adds. "So in other words jobs that may induce cancer because of the disruption of your sleep rate rhythm." That's pretty scary.
4. Heart health
During deep sleep, as well as getting a rest, your body experiences what Walker describes as a "reboot of the cardiovascular system". Your heart rate drops and your blood pressure goes down, both of which are vital for good heart health.
"If you're getting six hours of sleep or less, you have a 200% increased risk of having a fatal heart attack or stroke in your lifetime," explains the neuroscientist. And there's some firm evidence to prove this correlation.
Every year in spring, we switch to Daylight Saving Time, where we lose an hour of sleep. Scientists believe it's no coincidence that medical records indicate a staggering 24% increase in heart attacks the day after the switch over – getting a full night's sleep really is important when it comes to keeping your heart healthy.
Watch the Tech Insider video in full here.
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