Why Sleep Needs Vary
Although everybody suffers from similar problems if deprived of sleep, the actual amount of sleep required in order for different people to be healthy is very variable. Most adults need between seven and nine and a half hours per night, but some can get by comfortably on just five and a half. Why is this, what factors are involved, and how can you work out what is right for you?
Sleep Needs and AgeThe amount of sleep we need varies throughout life. Newborn babies usually sleep for most of the day - as much as twenty hours - and this need for sleep gradually diminishes during childhood, but teenagers often find themselves needing around ten hours a night in order to feel fully alert during the day. This isn't because they're lazy, it's because their brains are undergoing major changes - a natural part of puberty - that mostly take place when they're unconscious.
Towards the end of their teenage years, most people settle into a sleeping pattern that will stay with them for the rest of their lives. It's a myth that people need less sleep as they grow older. Work patterns and health issues may mean that they gradually get less sleep but they will usually experience problems as a result. There is an important difference between the amount of sleep we can get by on and the amount of sleep we need.
Other FactorsA number of other factors also affect how much sleep we need. In general, men need half an hour to an hour per night more than women, though women are still more likely to get less than they need. Some genetic conditions, including poor blood clotting, are associated with a decreased need for sleep.
Many people find that they need more sleep in the winter than in the summer. This isn't just because it's easier to wake up when it's light outside. It's because lower light levels in general alter the chemistry of our bodies, altering their requirements. Because some people are more sensitive to these changes than others, the impact of seasonal changes varies.
The Body ClockAside from age, the most important factor affecting how much sleep we need is how much sleep we have become used to, especially during our early twenties. Good sleep habit at this stage of life can help to establish an instinctive rhythm that will keep us in good health later on and will reduce the risk of insomnia.
Unfortunately, problems with short term insomnia, especially in youth, can train the body clock in the wrong way. Retraining it is more difficult but there are an increasing number of therapies designed to help people do this, decreasing the risk of long term problems.
Varying Sleep PatternsPeople don't only sleep for different lengths of time at different stages of life - they also sleep in different patterns. Babies usually sleep in four to five hour bursts and are not at all sensitive to changes in light, which is why they're so good at waking up their parents at unreasonable times. Young children tend to function better if they can have naps in the afternoon.
Most people lose the instinct to nap as they enter adulthood, or deliberately suppress it because it interferes with working life. This is unfortunate as it can continue to play a useful role. If you have holidayed by the Mediterranean you may have met people who enjoy a daily siesta, a period of sleeping or dozing, around noon - this isn't only about avoiding the heat; it recharges the body for afternoon activities.
As the physical strain of old age increases tiredness, many people recover the napping habit. It isn't recommended for all types of insomnia as it can sometimes interfere with night-time sleep, but your doctor can help you work out if it could be useful to you.
Getting it RightUltimately, there is so much variation in individual sleep patterns that it's useless to pick the average number of hours and try to force your body to sleep exactly that much. What matters is finding the right level for you. If you are suffering from symptoms of insomnia, the chances are that you are getting too little, even if you're sleeping for eight hours a night.
When you get a break from working life, spending a few days without an alarm clock and letting yourself sleep and wake naturally can help you to work out your individual needs. Don't try to lie in past the point where it makes you feel fuzzy-headed, but get up promptly when you feel refreshed. This can help to re-establish healthy sleep habits.