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.
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.
Sleep is perhaps the greatest legal performance-enhancing “drug” that few people are taking advantage of. Obtain less than eight hours of sleep a night, and especially less than six hours a night, and the following happens: time to physical exhaustion drops by 10 to 30%, as does aerobic output; limb extension force and vertical jump height are reduced; peak and sustained muscle strength decrease. Add to this the cardiac, metabolic and respiratory effects: higher rates of lactic acid buildup and reductions in blood oxygen saturation with converse increases in carbon dioxide, due in part to a reduction in the amount of air that the lungs can expire in a sleep-deficient state. And then there is injury risk. Relative to sleeping nine hours a night, sleeping five to six hours a night will increase your chances of injury across a season by more than 200%.
Routinely sleeping less than six hours a night also compromises your immune system, significantly increasing your risk of cancer. So much so, that recently the World Health Organization classified any form of night-time shiftwork as a probable carcinogen.
Inadequate sleep – even moderate reductions of two to three hours for just one week – disrupts blood sugar levels so profoundly that you would be classified as pre-diabetic. Short sleeping increases the likelihood of your coronary arteries becoming blocked and brittle, setting you on a path towards cardiovascular disease, stroke and congestive heart failure. Sleep disruption has further been associated with all major psychiatric conditions, including depression, anxiety and suicidality.
Governments and health institutes must themselves become a voice that educates society about sleep. Put simply: sleep – a consistent seven- to nine-hour opportunity each night – is the single most effective thing we can do to reset our brain and body health each day