By Matthew Walker
Source: The Guardian
‘A consistent seven to nine-hour sleep each night is the most effective thing we can do to reset our brain and body health.’
Do you think you got enough sleep this past week? Can you remember the last time you woke up without an alarm clock, feeling refreshed, not needing caffeine? If the answer to any of these questions is “no,” you are not alone. Two-thirds of adults throughout all developed nations fail to obtain the recommended eight hours of nightly sleep.
Indeed, surveys by the UK Sleep Council and YouGov reveal that one out of every three people you pass on the streets of Britain regularly suffer from poor sleep. I doubt you are surprised by these facts, but you may be surprised by the consequences.
Insufficient sleep is now one of the most significant lifestyle factors influencing whether or not you will develop Alzheimer’s disease. During sleep, a remarkable sewage system in the brain, called the glymphatic system, kicks into high gear. As you enter deep sleep, this sanitisation system cleanses the brain of a sticky, toxic protein linked to Alzheimer’s, known as beta amyloid. Without sufficient sleep, you fail to get that power cleanse. With each passing night of insufficient sleep, that Alzheimer’s disease risk escalates, like compounding interest on a loan.
Parenthetically, and unscientifically, I have always found it curious that Margaret Thatcher and Ronald Reagan – two leaders who were very vocal, if not proud, about sleeping only four to five hours a night – both went on to develop the ruthless disease of Alzheimer’s. The current US president, Donald Trump – also a vociferous proclaimer of sleeping just a few hours each night – may want to take note.
Perhaps you have also noticed a desire to eat more when you’re tired? This is no coincidence. Too little sleep swells concentrations of a hormone that makes you feel hungry while suppressing a companion hormone that otherwise signals food satisfaction. Despite being full, you will still want to eat more. It’s a recipe linked to weight gain in sleep-deficient adults and children alike.
Worse, should you try to diet but don’t get enough sleep while doing so, it is futile, since up to 70% of the weight you lose will come from lean body mass, not fat. Turn these facts around and you realise that plentiful sleep is powerful tool for controlling your appetite, your weight and keeping your body trim.