The health complications and risk factors that arise from too little sleep, restless sleep and sleep disorders have become hot topics in the media over the past decade. However, the question of why we need to sleep is often left unanswered. There has been much research done which looks at the consequences of not having enough sleep or having restless sleep.

From these studies we can deduce that sleep is very important to cognitive, metabolic and physical recovery. Essentially, sleep is a state of recovery that is necessary for optimal daily function.

"Without sleep a person’s ability to perform complex tasks decreases, they become irritable, moody, lack concentration and are more susceptible to contracting illnesses."


Every day we wake up and begin to put our bodies through stress. Through the rigours of day to day life factors such as emotional stress, daily activity and exercise, the body is worn down little by little. Physically, the human body is a series of systems all working together to create an, ideally, healthy individual.

The only way to restore this series of systems is through sleep. There is a great deal of inter-individual difference in how much, when and how well one needs to sleep in order to function and feel good and often people can function well for periods of time on a limited amount of sleep. However, eventually if left unrestored, the systems will fail. Without sleep a person’s ability to perform complex tasks decreases, they become irritable, moody, lack concentration and are more susceptible to contracting illnesses.


Studies have shown that long-term lack of sleep or restless sleep causes one’s insulin sensitivity to de- crease. Metabolically, sleep greatly affects the body’s ability to utilize energy, in particular sugars. Lower insulin sensitivity reduces one’s glucose tolerance and this can cause glucose to be deposited as fat.

Furthermore, several studies have linked higher secretion of the hormone ghrelin to a lack of sleep and non-restorative sleep. This leads to the consumption of high-calorie dense foods and the central deposition of fat.

As a result of these hormone imbalances people who do not sleep are at a higher risk of be- coming obese and for contracting Diabetes, but, it often takes years of little restorative sleep to become obese and contract Diabetes.


One of the first things affected from a lack of sleep is one’s cognitive function. Sleep is necessary for learning, memory consolidation and concentration. Often after as little as one night of reduced or no sleep we feel these cognitive effects start to take place. In day-to-day life people feel themselves become forgetful and have a harder time making decisions at work and in daily life.

As well, the lack of sleep makes it harder to make judgments about one’s own level of impairment which can lead to dangerous behaviours like driving drowsy. All of this can make a bad night’s sleep look very grim. But, if you get the amount of sleep you need, take short naps to make up sleep debt, feel rested when you wake in the morning and sleep when you’re tired rather than when you think you should go to bed your body and mind will be well restored.

Remember every day you build a sleep debt that needs to be recovered at night in order to function well physically and mentally.