Seven things to know about sleep as the clocks go back
whole range of disorders.
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.
Studies have shown that depriving people of enough sleep for only a few nights in a row can be enough to put healthy adults into a pre-diabetic state.
These moderate levels of sleep deprivation damaged their bodies’ ability to control blood glucose levels.
Vaccines are less effective when we are sleep deprived, and sleep deprivation suppresses our immune system making us more prone to infection.
One study found participants who had fewer than seven hours of sleep were almost three times more likely to develop a cold than those who slept for seven hours or more.
People who don’t sleep enough also appear to produce too much of the hormone ghrelin, associated with feeling hungry, and not enough of the hormone leptin, associated with feeling full, which may contribute to their risk of obesity.
There are also links to brain function and even in the long term to dementia.
Professor Shane O’mara explained that toxic debris builds up in your brain during the course of the day and waste is drained from the body during sleep.
“If you don’t sleep enough, you end up in a mildly concussed state.”
The impact of sleeping too much is less understood, but we do know it is linked to poorer health including a higher risk of cognitive decline in older adults.
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.
The first stage in each cycle is a drowsy, relaxed state between being awake and sleeping — breathing slows, muscles relax, the heart rate drops.
The second stage is a slightly deeper sleep — you may feel awake and this means that, on many nights, you may be asleep and not know it.
Stage three is deep sleep. It is very hard to wake up during this period because it is when there is the lowest amount of activity in your body.
Stages two and three together are known as slow wave sleep which is usually dreamless.
After deep sleep we go back to stage two for a few minutes, and then enter dream sleep, also called REM (rapid eye movement). As the name suggested, this is when dreaming happens.
In a full sleep cycle a person goes through all the stages of sleep from one to three, then back down to two briefly, before entering REM sleep.
Shift workers get sick more often
Shift work has been associated with a host of health problems. 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.
People who work shifts are significantly more likely to take time off sick, according to figures from the Office for National Statistics.
There is a far bigger gap for nonmanual workers than manual workers — lack of sleep seems to have a bigger impact on those doing more sedentary jobs.
Many of us are feeling more sleep deprived than ever
To judge from media reports, you’d think we were in the grip of a sleeplessness epidemic. But are we really all more sleep deprived than before?
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 an evidence suggested 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.
So why do so many people report feeling tired?
It may be that this problem is concentrated in certain groups, making the trend harder to pick up on a population-wide level.
Sleep problems vary considerably by age and gender, according to one study of 2,000 British adults. It found women at almost every age have more difficulty getting enough sleep than men.
The sexes are more or less level at adolescence but women begin to feel significantly more sleep deprived than men during the years where they may have young children, while work may become more demanding. The gap then shrinks again later in life.
Caffeine affect sleep duration and quality.
Phones are keeping teenagers awake
Sleep experts said teenagers need up to 10 hours sleep a night, but almost half don’t get this much according to the NHS.
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.
We have more different types of entertainment on offer than ever, making the temptation to stay awake greater.
The blue light emitted by electronic devices makes us feel less sleepy. And the activity itself — be it talking to friends or watching TV —stimulates our brain when it should be winding down.
Morning larks, night owls?
There have always been morning people and evening people. We even have genetic evidence that backs this up.
But the introduction of artificial light appears to have exacerbated this effect, particularly for people who prefer to stay up late.
If you are already inclined towards being a night owl, artificial light will make you stay up even later.
About 30 percent of us tend towards being morning people and 30 percent towards being evening people, with the other 40 percent 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.
*Rachel Schraer and Joey D’urso are BBC journalists.