From better sex to thicker hair, why a good night’s sleep is worth celebrating

A good night’s sleep is important, but why? Here’s what happens while we sleep – and what can happen if we don’t get enough rest.

While we are asleep, the body’s immune system produces cells and proteins which protect us against infection and illness, says psychologist Esther Yuet Ying Lau. In addition, the body secretes human growth hormone (HGH), which helps it maintain and repair skin, muscle and bones. HGH is particularly important for growth in adolescents.

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“Research shows that [cell production] doubles during REM (rapid eye movement) sleep,” says Lisa Griffiths, a homeopath at The Round Clinic in Hong Kong. “Without sleep, our central nervous system rapidly loses the ability to maintain healthy function and our bones and muscles do not get the necessary growth hormone to repair and rejuvenate.”

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Detoxification also takes place during sleep. Cerebrospinal fluid, a clear liquid surrounding the brain and spinal cord, moves through the brain, clearing it of the by-products of substances processed by the body – while waves of electrical activity in the gut sweep waste out of the digestive system.

Sleep also boosts brain health by allowing the organ to rest and repair itself. “Brain activity changes in patterns that can be classified into REM and non-REM sleep,” says Dr Vanessa Wong, a psychiatrist at Hong Kong Adventist Hospital. “The former is associated with dreaming and is thought to assist in brain development, while the latter can be broken down into very light, deeper and slow-wave deepest sleep. Cycles of REM [and non-REM sleep] last around 50 minutes in children [and] 90 minutes in adults, and the proportion of deep sleep to light sleep decreases with age.”

Lau says a restful sleep can help us solve problems. “In one of my recent studies, we found that an afternoon nap can improve a person’s working memory. This in turn helps support many cognitive functions, like reading comprehension, mathematical problem-solving and multi-tasking.”

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And it’s not called beauty sleep for nothing. Griffiths points out that a good night’s sleep is essential to skin and cellular rejuvenation. “This process happens on a hormonal level, with a reduction in cortisol, which thins the skin, and an increase in HGH and melatonin, which heals the skin. The obvious benefits of getting enough rest include fewer wrinkles, brighter eyes, thicker hair and an overall better and healthier appearance.”

Sleep is also a chance for our muscles to relax. This includes our heart. “Our heart rate and blood pressure drop while we are asleep, giving our heart a break,” explains Lau, assistant professor in the Department of Psychology at The Education University of Hong Kong’s Centre for Psychosocial Health.

This is probably the reason people with sleep disorders such as obstructive sleep apnoea have a higher risk of developing cardiovascular diseases, says Dr David Ho, an ear, nose and throat specialist at Matilda International Hospital in Hong Kong. “In people with long-term obstructive sleep apnoea, the heart muscle is actually thicker because it’s had to beat faster and work a lot harder in order to get enough oxygen to the brain during the night. If this thickening of the muscle worsens, it can increase the individual’s risk of developing high blood pressure and a heart attack.”

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A good night’s sleep might also do wonders for your sex life – particularly that of elderly women. A new US study of 93,668 women aged 50 to 79 linked sleep problems and sexual dissatisfaction. The findings, which were published in February in the journal of The North American Menopause Society, Menopause,revealed that women who had less than seven to eight hours of sleep a night experienced lower odds of sexual satisfaction. Since the prevalence of sleep problems increases with age, it’s not just menopause, but also issues like insomnia that can affect sexual pleasure in an older woman.

Dr Wong says sleep deprivation has been linked to diabetes, hypertension, heart disease, mood disorders, a weakened immunity, increased inflammation due to a rise in cortisol, and lower life expectancy. It is also associated with increased appetite, higher alcohol consumption, and obesity, which increases the risk of metabolic syndrome – biochemical and physiological abnormalities associated with the development of cardiovascular disease and type 2 diabetes.

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“Plus, when we are sleep-deprived, it is harder for us to concentrate, to remember and to engage in complex logical thinking,” says Lau. When we are mentally fatigued and cannot focus, our risk of having a serious accident also increases.

The optimal amount of sleep for most adults is seven to eight hours, while teenagers need nine to 10 hours and younger children more than 10 hours of sleep a night.

When it comes to restful sleep, quality is key. You should be able to fall asleep easily and sleep mostly undisturbed during the night. When you wake up, you should feel alert, refreshed and ready to take on the day.

Experiment with different sleep positions to figure out what works best for you. If you have obstructive sleep apnoea, sleeping on your side may provide a better night’s sleep than sleeping on your back. “Sleeping on your side may help improve airflow,” says Dr Josna Adusumilli, a neurologist and sleep disorders physician at Massachusetts General Hospital.