With our busy lifestyles, it’s common for many people to cut back on their sleeping hours when short on time. Often this is because sleep is viewed as an optional luxury, when in fact getting enough sleep is as essential for good health as food and air. We need around eight hours of sleep every night,1 and when we consistently get less than that, we have a higher risk of developing chronic diseases and experiencing other negative impacts on our overall wellbeing.
According to an Australian study on the levels of tiredness and sleeping habits, 96% of participants reported that they feel constantly tired upon waking.5
Risk of developing serious medical conditions
While other factors – such as genetics, nutrition, and inactivity1 – can play a part in chronic or long-term conditions, sleep appears to have an important role when it comes to the risk of serious medical conditions such as obesity, diabetes, and heart disease, and most experts1 believe sleep is just as important as exercise and nutrition.
Obesity – Sleep deprivation has been linked with obesity.2 Studies have shown that those who regularly logged less than six hours of sleep each night were more likely to be overweight while those who had an average of eight hours per night were found to have the lowest relative body fat.1 Sleeping less than six hours a day has been associated with nearly 30 per cent increase in likelihood of obesity compared with those who slept seven to nine hours.3 Lack of sleep can make you eat more because it lowers levels of the hormone leptin – which helps with appetite regulation – while increasing ghrelin, a chemical that stimulates your appetite.2
Diabetes – People who sleep less than five hours each night on a consistent basis have a higher risk of either having or developing type 2 diabetes.4 If you don’t get enough sleep, you’re more likely to release more insulin in your body, which is associated with type 2 diabetes and fat storage.2
Cardiovascular disease and hypertension – Sleep deprivation can lead to an increased risk of heart disease, hypertension, and high blood pressure.4 Research shows that even modest deprivation (just one or two hours less than the standard eight hours) can significantly increase the risk of coronary artery calcification, which is a predictor of heart attacks and death due to heart disease.1
Shortened lifespan and higher risk of death
Some studies have linked sleep deprivation with a shortened lifespan and risk of death.3 A study of over 10,000 people over two decades found that those who reduced their sleep quantity from seven to five hours or less each night almost doubled their risk of death from various causes, including cardiovascular disease.3 Another study found sleeping less than five hours per night increased the risk of death by all causes by 15 per cent.2
Lowered immune function
Sleep promotes the production of protective cytokines, antibodies, and cells that help fight off infections.2 Without adequate sleep, your immune system is less likely to be able to resist infection as effectively, so you take longer to fend off illnesses and recover from them.1
Related to the impact on immune function is the relationship between sleep deprivation and colds and the flu.2 Studies show that of all study subjects exposed to the rhinovirus, those who slept less than seven hours on average each night were about three times more likely to develop cold symptoms than those who slept eight or more hours each night.1
Poorer cognitive function and mental wellbeing
In addition to long-term condition and the immune system, sleep deprivation can also lead to reduced cognitive functioning and poor mental and emotional wellbeing. For example, sleep deprivation (less than six hours a night) has been linked with depression and anxiety,4 as well as poor judgment, and lower mental alertness and performance.3
On the flip side, there’s also research to show that deep sleep positively affects your memory. Sleep deprivation that leads to fatigue could increase the risk of car accidents3 and more workplace injuries and accidents. All of these factors can contribute to declining productivity and effectiveness in your work and private life, as well as a decline in overall wellbeing.1
Sleep deprivation can have a negative impact on fertility by lowering reproductive hormones. In turn, this can have a twofold impact on fertility by reducing sex drive while directly impacting the ability to conceive.4
Significant sleep debt over the longer term can cause excessive levels of the stress hormone cortisol, which in turn can break down skin collagen in the body. This can then result in premature ageing. By the same token, sufficient deep sleep or slow-wave sleep promotes the release of human growth hormone, which plays a role in repairing the body’s tissue.6
The role of sleep in wellbeing
Getting sufficient sleep is not the sole factor in achieving great health but it’s nevertheless an important contributing factor, as the research shows.1 Sleep promotes cell and tissue recovery, muscle growth, and protein synthesis while supporting good mental function.2 This means getting enough sleep should be a major priority for everyone.
For those who want better health and quality of life, sufficient quantities of sleep should rank as high as eating well and getting enough exercise.