Although still not fully understood, sleep is vital to health. We have all experienced the effect of just one poor night’s sleep on our mood, making us feel low, negative and irritable. It also affects concentration, memory and energy levels. A chronic lack of sleep can lead to other health problems that we are not even aware of in the short term, but that can have serious, even fatal, consequences in the longer term.
It can be helpful to understand why sleep is so important in order to find the motivation to prioritise optimising sleep quality and quantity, which is why I am focusing on the why we sleep here before moving onto how to optimise sleep in the next post. As sleep affects the whole body, I will break it down by system: nervous, circulatory, endocrine and immune.
Given how we feel after one bad night, it is no surprise then that chronic poor sleep can lead to mental health problems such as depression and anxiety. It also adversely affects reaction times to the point that even moderate sleep deprivation can impair mental performance just like alcohol consumption can, which means that there are a lot of tired people driving around as dangerously as if they were drink driving without even realising it. Worse still, if you fall asleep at the wheel, albeit momentarily, you don't react at all. At least someone under the influence of alcohol reacts, albeit slowly, which can make driving when sleep deprived even more dangerous than drink driving, and, sadly, it frequently is.
The lymphatic system drains waste from the whole body except the brain. The brain has its own waste disposal system: the glymphatic system. The main waste product in the glymphatic system is amyloid beta, high levels of which are found in the brains of people with dementia. Studies have found that the glymphatic system is 60% more productive when we are asleep. Even people genetically at risk of developing dementia can delay onset and/or reduce the risk by improving their sleep quality. Parkinson’s disease has also been linked to poor sleep quality.
Sleep apnoea is a condition in which the airway closes during sleep causing frequent waking. It has been found to increase the risk of high blood pressure, heart attack, heart failure and stroke. Studies have shown that poor quality sleep of any form can increase the risk of raised blood pressure.
A chronic lack of sleep can lead to obesity for several reasons: it affects the hormones that govern hunger, it reduces impulse control, and the feeling of a lack of energy after a poor night’s sleep can prompt us to eat to compensate. Chronic sleep problems interfere with sugar regulation in the body and so can increase the risk of diabetes.
Without sufficient sleep, the immune is unable to function properly leading to increased vulnerability to infections, inflammation and even cancer.
Don’t panic! The odd night of poor sleep won’t do you any long-term harm. If you do have a chronic problem with your sleep, there is action that you can take to improve it and to reduce your risk of developing disease, which I will cover in the next post. Sleep supports relaxation, healthy food choices and an active lifestyle, and relaxation, a good diet and exercise promote sleep, which is why sleep can be seen as the foundation of the other pillars of health. If you want to read more about the four pillars of health, I can recommend Dr Rangan Chatterjee's book The 4 Pillar Plan.