Enjoy Restful Sleep
Restful sleep and sound mental and physical health are closely related. In the video below I explain why, for adults, eight hours a night, not much less and not too much more, are so important. I also explain why our modern lifestyle often gets in the way of a good night’s sleep and provide practical steps to ensure that you do.
Why do I need to sleep?
No one really knows! Even researchers, who have devoted a lifetime to the subject, are unable to offer satisfactory explanations of why most animals need to sleep. They cannot even agree on a possible answer.
Some suggest we sleep to conserve energy or restore the metabolic balance of the brain. Others claim that sleep enables the brain can make sense of information gathered during the day. At the time of writing the jury is still out.
How much sleep do I need?
It used to be believed eight hours was the ideal. Anything less was claimed to cause to fatigue throughout the day, an inability to concentrate, a risk of errors and, when chronic, lasting damage to the sleep deprived individual’s mental and physical well-being.
More recent work has shown that our need for rest varies considerably through life and that too much sleep can be as detrimental as too little.
So, what’s the right amount?
The answer depends your age.
Between two and four months’ infants tend to sleep more at night than during the day and for five or six hours at a stretch. By six months, around six out of babies sleep through the night at by nine months 80% will do so.
The most critical change occurs in puberty. Teenagers, as any parent will testify, tend to find it very hard to get up in the morning. This is due to a resetting of their biological clock and has nothing to do with laziness. In recognition of this some educational authorities now start morning classes slightly later. The ability to sleep declines with age, for reasons I will give in a moment.
I am at my brightest first thing but slump as darkness falls, why is this?
Some people are at their best early in the morning while others only do so later in the day. Sleep researchers have called these two groups ‘Larks’ and ‘Owls’.
It’s all down to their biology and something called their circadian (‘around the day’) rhythm. This controls the approximately 30 F. rise and fall in our temperature during the course of 24 hours. As our temperature rises we feel more alert. As it falls we feel sleepy.
In some people, body temperature peaks around 6pm to 7pm with a small drop in body temperature around 3pm, which accounts for the popularity of the afternoon siesta. This is followed by a more significant drop around 2am – 3am.
It is no co-incidence there is a small rise in fatigue-related traffic accidents around mid-afternoon and a large increase around between 2am and 3am.
Our circadian rhythm is set both by exposure to natural light and darkness.
The amount of light that our eyes receive controls the production of the sleep hormone melatonin. Melatonin is produced in our retinas and in the pineal gland in the brain. When melatonin levels are high, body temperature starts to fall and sleepiness increases.
Melatonin levels drop with age. Which is why older people tend to sleep for shorter periods. Many for only around 6 hours a night compared to around 16 hours for a young baby, 9 hours for a teenager and between 7 and 8 hours for a younger adult.
Sleep Loss Dangers
While some people need less sleep than others, there is a minimum below which the brain simply cannot functioning efficiently.
Studies suggest that individuals who sleep between 5 and 6.5 hours a night are likely to live longer than those who sleep either less than five or more than seven hours a night.
In recent years the number of hours of undisturbed sleep has fallen dramatically, in both the developed and developing world. To compound the problem many now work night shifts or, even more damagingly, split-shifts which disturbs their natural bodily rhythms to an even greater extent.
Four lifestyle factors have, traditionally, been shown to reduce the risk of a heart attack. (1) Regular exercise. (2) A nutritious diet, drinking. (3) Alcohol only in moderation. (4) Not smoking.
Between them, they reduce the risk of a heart attack by more 57% and of a fatal attack by 67%. When seven or more hours sleep each night is added to these factors, the risk falls to 67% and 83%.
In an experiment I conducted at the famous race track Brands Hatch, a group of motorists, including professional driver Jason Plato, were prevented from sleeping for 24 hours and the disastrous effects on their driving ability monitored.