Why is sleep important and how much do we need?

Getting the right amount of sleep is critical, with too little sleep on a regular basis leading to short and long-term health consequences.

Short-term symptoms of lack of sleep include reduced cognitive function and therefore ability to perform day-to-day tasks, such as solving problems, concentrating and memorising information.

Reaction times are also slowed and mood can be affected, with sleep-deprived people more likely to become irritable.

Man resting his face on both of his hands

All of these symptoms can increase the risks of potentially costly or dangerous accidents when awake, according to Harvard Sleep Medicine.

Your immune system also suffers from a lack of sleep. A 2010 study found that those who slept less than six hours a night the week prior to being exposed to a cold (virus) by nasal drops were 4.2 times more likely to catch the cold compared to those who got more than seven hours of rest a night.

And if sleep deprivation continues long term, then it can contribute to more serious health conditions such as obesity, type 2 diabetes, cardiovascular disease and poor mental health.

Studies have linked these health conditions with short term effects of sleep deprivation including increased stress and blood pressure, impaired control of blood glucose and increased inflammation.

Sleep and obesity:

Studies have consistently found that a lack of sleep increases the likelihood of obesity.

Those who regularly sleep less than six hours per night generally have a higher than average body mass index (BMI) than people who rested eight hours, who have the lowest BMI, according to Harvard Sleep Medicine.

“During sleep, our bodies secrete hormones that help to control appetite, energy metabolism, and glucose processing. Obtaining too little sleep upsets the balance of these and other hormones,” they state, adding that the tiredness associated with insufficient sleep may also contribute to reduced levels of exercise.

This can then enter people into a vicious circle, as those who are overweight are more likely to experience obstructive sleep apnoea, which will serve to further reduce sleep quality and length.

Sleep and alcohol:

While many people think alcohol’s sedative properties help them snooze, it actually reduces sleep quality.

Alcohol affects the all-important rapid eye movement (REM) sleep stage, which can be reduced or not occur completely. Then, as alcohol is processed by the body, it begins to stimulate parts of the brain. This means you will wake feeling less rested than you otherwise would have.

Alcohol also contributes to snoring and potentially, obstructive sleep apnoea.

How much sleep do we need?

The amount of sleep required varies from person to person, however most adults require seven to eight hours of quality sleep each night.

However, individual rest needs can range from five to ten hours each night, according to SA Health.

Judging sleep needs should be done on an individual basis. “If we do not feel sleepy and fatigued, then our sleep is adequate, even if it is not the average length of time,” SA Health says.

Furthermore, the first three to five hours of sleep – known as core sleep – are thought to be the most important and it may be possible to function normally during the day if you obtain this type of sleep.

However, an ongoing lack of sleep does put you at risk of the numerous short and long-term health consequences.

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