People across the UK will wake up having gained an hour’s sleep on Sunday morning, as the clocks go back heralding darker evenings and shorter days. But how much do we know about sleep and its impact on our lives, from our health and mood, to how long we’ll live?
1. We’re told to get our eight hours.
Studies carried out around the world, looking at how often diseases occur in different groups of people across a population, have come to the same conclusion: both short sleepers and long sleepers are more likely to have a range of diseases, and to live shorter lives.
Short sleepers are generally defined as those who regularly get less than six hours’ sleep and long sleepers generally more than nine or 10 hours’ a night.
2. What happens in your body when you don’t sleep enough?
A review of 153 studies with a total of more than five million participants found short sleep was significantly associated with diabetes, high blood pressure, cardiovascular disease, coronary heart disease and obesity.
3. We need different types of sleep to repair ourselves.
After we fall asleep we go through cycles of “sleep stages”, each cycle lasting between 60 and 100 minutes. Each stage plays a different role in the many processes that happen in our body during sleep.
4. Shift workers who have disturbed sleep get sick more often.
Researchers have found shift workers who get too little sleep at the wrong time of day may be increasing their risk of diabetes and obesity.
Shift workers are significantly more likely to report “fair or bad” general health according to a 2013 NHS study, which also found people in this group were a lot more likely to have a “limiting longstanding illness” than those who don’t work shifts.
5. And many of us are feeling more sleep deprived than ever.
A big piece of research looking at data from 15 countries found a very mixed picture. Six showed decreased sleep duration, seven increased sleep duration and two countries had mixed results.
Lots of a evidence suggests the amount we sleep hasn’t changed that much in recent generations.
But if you ask people how sleep deprived they think they are, a different picture emerges.
- Average sleep time is 6.8 hours, below the average 7.7 hours people feel they need
- More than half (54%) have felt stressed as a result of poor sleep
- More than a third (36%) have eaten unhealthy food as a result of poor sleep
- Almost four in 10 (37%) have fallen asleep on public transport.
6. But we didn’t necessarily always sleep this way.
Roger Ekirch, a history professor at Virginia Tech in the USA, published a paper in 2001 drawn from 16 years of research.
Dr Ekirch uncovered more than 2,000 pieces of evidence in diaries, court records and literature which suggest people used to have a first sleep beginning shortly after dusk, followed by a waking period of a couple of hours, then a second sleep.
7. Phones are keeping teenagers awake.
Bedrooms are supposed to be a place of rest but are increasingly filled with distractions like laptops and mobile phones, making it harder for young people to nod off.
68% of young people think using phones at night affects school work
45% check their phone after going to bed
10% do so more than ten times per night
8. Testing for sleep disorders is on the up.
More people are turning up at their doctors complaining of problems sleeping.
Analysing data collected by NHS England, the BBC found in June that the number of sleeping disorder tests had increased every year over the past decade.
9. Are other countries doing it differently?
One study looked at sleep habits in 20 industrialised countries.
It found variations of up to an hour in the time people went to bed and woke up, but overall sleep duration was fairly constant across countries. Generally, if a population on average went to bed later, they woke up later too, although not in every case.
Researchers have concluded that social influences – hours worked, timing of school, leisure habits – play a far bigger role than the natural cycle of light and dark.
10. Morning larks, night owls?
About 30% of us tend towards being morning people and 30% towards being evening people, with the other 40% of us somewhere in the middle – although marginally more people prefer early rising to late nights.
We do have some control over our body clocks, however. Those who are naturally late to bed and late to rise can try reducing their exposure to light in the evenings and making sure they get more light exposure in the daytime.