SLEEP: Are you a morning lark or a night owl? How much sleep do you need?
1. Sleep duration not only varies between individuals, but it changes with age.
A newborn baby may need between 14-17 hours a day, but by the time he is in school, his sleep requirement has typically dropped to 9 to 11 hours. This drops by about one hour in adolescence then stabilises in adulthood.
2. The average sleep duration for an adult is between 7 and 9 hours.
But even this can be misleading as this is the average range and doesn’t include the natural extremes. While the majority of people fall within this range, there are naturally short sleepers and others are naturally long sleepers. Trying to sleep for less than your own individual sleep requirement will lead to sleep deprivation. Equally, trying to sleep for more than your natural sleep duration will lead to problems such as not being able to fall asleep or waking in the night unable to get back to sleep. It’s the same with sleep timing – your preferred wake up time or going to sleep time is unique to you; some people are naturally night owls; some are morning larks and other people fall in between. This is referred to as your circadian rhythm. Genetics is likely to play a part in this but sleeping patterns are also heavily influenced by light.
3. What is the best sleep duration?
There has been a wealth of research looking at short and long sleepers and associated health problems. These studies have found both short sleep (less than 6 hours) and long sleep (more than 10 hours) are associated with a number of long-term health conditions such as cardiovascular disease, obesity, certain cancers, mental health problems and reduced life expectancy. While these findings are alarming, it’s important to understand that these studies are saying there is a link between sleep duration and health. The studies are not saying that short or long sleep duration causes these health problems; indeed, it could be the other way around i.e. that short or long sleep is due to an underlying health condition. Or it could be that other factors are linking sleep duration and health conditions together so there is no direct link.
Having said all that, there is now a fairly large, reliable body of evidence to say that sleep deprivation leads to health problems. So, we should all aim to avoid sleep deprivation. Generally, less than six hours is too little, excluding, of course, those rare individuals mentioned previously. The clearest indication that you are sleep deprived is that you feel excessively sleepy in the day. Or, in fact, you are actually falling asleep during the day. Sleepiness is different to tiredness; the latter doesn’t necessarily lead to sleep.
4. What about napping?
There are mixed opinions about napping. If you are sleep deprived, napping is clearly essential. But ideally it’s best to get more sleep at night. However, if you get enough sleep at night, but still find a short nap beneficial in the day, then that’s a good thing so keep doing this! 10-15 minute is best before 3pm. However, if you are struggling to sleep at night, the advice is no nap during the day because this may affect your nocturnal sleep, particularly if you nap for a long time and too late in the day. Remember napping includes dozing off in the evening in front of the TV.
5. How to find your own perfect sleep duration?
The best way to find your own optimal sleep duration is on holiday. For many people, the first few days of holiday may involve clearing a “sleep debt” caused by travel-induced sleep deprivation or getting over jetlag, so discount these first few nights. After this your sleep duration should stabilise. Keep a record of when you start to feel naturally sleepy at night and go to bed at this time (be aware this will be influenced by alcohol and other stimulants so it’s best to avoid them. Sleep without an alarm clock and see when you naturally wake in the morning. Keep a sleep diary that records these times over a period of a week, and then calculate your average sleep duration over a period of 7 to 14 days. This is different to your time in bed. From this diary you will get good estimate of your optimal sleep duration and see a pattern emerge around your preferred time of going to bed and waking up. This is a good indication of your natural circadian rhythm or body clock.
6. ‘Listen’ to your body and the signals it gives you.
Once you have worked out your natural rhythm t’s important to continue looking out for your signs of sleepiness (increased yawning, a feeling that you will nod off, droopy eyes etc.) and to go to bed at this time. Don’t follow someone else’s pattern. You will also need to dim the lights in the evening and to spend a good amount of time outside in the day as this will strengthen your circadian rhythm. You don’t necessarily have to have eight hours of sleep – you may need more or less than this; work out what is best for you. Your approach to sleep should be to find your own natural sleep duration and timing.