What is normal sleep?
By Dr Alison Bentley, Restonic Sleep Expert
What is normal sleep?” It’s not a strange question really. But while books and Google insist that normal sleep is 7-8 hours long, in one go from 10pm to 6am, how many of us actually sleep like that? I find that people whose sleep differs from this ideal often believe they have a sleep disorder. However, that’s not necessarily the case. There is some room for deviation from commonly cited “normal sleep”, in terms of three main components: duration, timing and solidity.
It is often quoted that 7-8 hours of sleep is the norm. That is not quite true. When looking at the duration of sleep in a population, the average is 7-8 hours, but there are quite a few people who sleep less than that and others who need more sleep.
If a person only sleeps five hours a night, they may either have insomnia or they may be a naturally short sleeper. The difference lies in how they function during the day. The naturally short sleeper copes well and doesn’t feel tired, while the person with insomnia feels tired and fatigued with a deficit in attention resulting in poor concentration and memory difficulties.
If you are a naturally short sleeper there is no natural way to increase the number of hours slept and that is the ‘normal’ for you.
Many people sleep between 10pm and 6am, but again there is variation. Some people are like larks and go to bed early and wake early – feeling refreshed and ready to go to gym at 5am. Others are owls, preferring to stay up late and sleeping in a little later as well.
Whether you are a lark or an owl is also genetically determined. While it is possible to override your natural timing you will always feel a little jet-lagged. Owls can wake up at 5am, but will not wake up feeling refreshed and will instead feel tired and grumpy until their usual wake-up time.
Solidity of sleep refers to the expectation that sleep during the night should occur in one solid block. However, that never really happens because we actually wake up every 90 minutes. These wake-ups are very short and good sleepers don’t remember them. It is believed that we wake up just to check the environment.
If you extend your sleep duration by an hour those wake-ups are also likely to expand, meaning that when you wake up normally you may stay awake for longer.
Sometimes, the first three hours of sleep stay intact with multiple awakenings after that. There is an assumption that any period spent awake during the night must be abnormal. However, literature from centuries ago would suggest that it was normal to go to sleep as soon as it got dark followed by a few hours spent awake during the night and another few hours of sleep before starting the day. So, sleep would be in two pieces – and that was normal.
Sleep can be shorter or longer than 7-8 hours, occur earlier or later, and have gaps and still be normal.
The most important thing is that you need to feel that you have had enough sleep when you wake up – you are not sleepy during the day.
Good daytime function is a better measure of normal sleep, rather than the right numbers for your sleep at night.
Conversely, if you get the right numbers for your sleep but still feel tired and sleepy during the day that may indicate an important sleep disorder. If this is the case, consider speaking to a healthcare professional.