We all need to sleep, and lack of sleep is linked to depression, behavioural disorders and some of our leading preventable diseases including obesity, heart disease and diabetes. According to a recent poll of 2000 adults by the Royal Society for Public Health, we only get an average of 6.8 hours a night, far less than the 7-9 hours per day recommended for 18-64 year olds.
The first step to better sleep, is understanding it. With that in mind, here are 10 facts you may not know about slumber.
1. You are paralysed when you are dreaming
Although you can still move your limbs when you are in the first stages of sleep, known as shallow, deeper and deep sleep, which lasts up to 100 minutes, you are rendered completely helpless when you enter REM (Rapid Eye Movement) sleep which is the only time you dream. Throughout the night, you cycle through stages of sleep and periods of REM sleep typically last around 25 minutes before you go back to shallow sleeping and even brief wakefulness.
Paralysis during REM sleep occurs because the neuromuscular junctions are temporarily interrupted so nerve impulses cannot travel to the muscles. “There is a very good reason for this,” explains Professor Kevin Morgan, director of the Clinical Sleep Research Unit at Loughborough University. “If you were not paralysed, you would literally ‘act out’ your dream.” There are some people who have disorder which means that they can move during REM sleep and they thrash around for these periods, sometimes causing themselves injury.
2. You wake up taller
It’s not just an old wives tale. This is true for all of us. Lying horizontal for hours at a time allows the body’s skeletal structure, cartilage and muscles to stretch out by millimetres. So when you wake up in the morning, you are fractionally taller for the first hour or so than you will be in the afternoon. Children grow most during deep sleep, which is the only time when the body releases plentiful quantities of Human Growth Hormone. “In youngsters, human growth hormone is secreted during deep sleep so there may be a direct effect, but also sleep is a time of enforced rest and recovery, so nutrients are not used up expending energy,” explains Dr Chris Idzikowski, of the Sleep Assessment and Advisory Service. By the time we grow up, HGH no longer serves this function although it does affect the appetite and supports the immune system throughout life.
3. Your fat cells need sleep too
It used to be thought that it was only the brain that needed shut-eye in order to store memories and rest. Recent research has revealed that all the cells in the body need sleep – periods where the metabolism slows right down – including fat cells. Scientists found that if they don’t get their rest, fat cells lose up to 30 per cent of their ability to respond to insulin, a hormone that regulates energy. This could lead to diabetes and other metabolic disorders.
4. Alcohol is the enemy of good sleep
A little tipple before bedtime isn’t going to do you any harm – as long as you keep the measures moderate and are used to it, but don’t think that alcohol is sleep tonic. According to a Sleep Council study, as many as 7.9 million have used alcohol to help them get to sleep at night.
Although alcohol helps you get to sleep very quickly, you won’t have a good restful night. “Alcohol is metabolised very quickly in the body so its sedative effect wears off and you have unpleasant withdrawal effects – usually around 2am in the morning,” says Professor Kevin Morgan. “You may find yourself wide awake and feeling terrible just when everyone else is fast asleep.”
Studies also show that alcohol consumption increases the amount of deep sleep, but reduces the amount of all-important REM sleep, which is the period when data from the day is processed and stored safely away. Lack of REM sleep can have a detrimental effect on concentration, motor skills, and memory. Dr Chris Idzikowski says: “REM sleep is also important because it can influence memory and serve restorative functions. Conversely, lack of REM sleep can have a detrimental effect on concentration, motor skills, and memory. REM sleep typically accounts for 20 to 25 percent of the sleep period.”
5. Your work patterns affect your sleep
Shift workers are more likely to suffer poor sleep. Chronic poor sleep affects 60-80 per cent of shift workers and one of the reasons could be that the human body really isn’t designed to be active in the night. We all have an internal body clock that follows regular patterns throughout a 24 hour period altering many important functions like body temperature, heart rate, blood pressure, respiration rate and hormone production.
The body never adjusts to the sleep/wake cycle imposed by shift work, even after extended periods. However, some partial adjustment may occur over successive shifts, but reversion to normal patterns usually occurs on days off.
Working long hours – over 48 hours each week – is also likely to have a bad effect on your sleep, particularly if you are female, according to a large-scale study, Understanding Society 2011. Dr Mark Bryan, formerly of the Institute for Social and Economic Research and now a reader in economics at the University of Sheffield, says that the findings were worrying but not unexpected. “The reduction mainly shows up as an increase in short sleep durations (less than six hours per night) rather than a reduction in long durations (more than 8 hours per night), and especially among women: 14 per cent of women working more than 48 hours sleep less than 6 hours per night, compared to 9 per cent of women working 31-48.
“The fact that there is little effect of long-hours working (compared to standard full-time) on long sleep durations suggests that time constraints are not the main reason for the lack of sleep. Other reasons, like stress, may be more important.” He also points out that there was a strong relationship between job satisfaction and sleep quality.
6. Too little sleep is linked to cancer
Lack of sleep has many bad health effects, they say, including obesity, hypertension and diabetes. It has been attributed to raising the chances of a woman getting breast cancer by as much as 60 per cent, because melatonin, a hormone produced by the brain during sleep to regulate the body’s internal clock, plays a key role in preventing breast tumours by suppressing the amount of oestrogen that is released.
A 2011 US study also found for the first time that getting less than six hours sleep a night was a risk for colon cancer.
Dr. Li Li of University Hospitals Case Medical Center and Case Western Reserve University School of Medicine says people who average fewer than 6 hours of sleep a night had an almost 50 percent “increase in the risk of colorectal adenomas compared with those sleeping at least 7 hours per night.
Adenomas are a precursor to cancer tumors, and left untreated, they can turn malignant, Li says.
“To our knowledge, this is the first study to report a significant association of sleep duration and colorectal adenomas,” Li says in a statement. “A short amount of sleep can now be viewed as a new risk factor for the development of the development of colon cancer.”
7. Too much sleep could shorten your life
The idea of sleeping like a baby (newborns need around 17 hours sleep every 24) may sound appealing but too much sleep is bad for your health. “People who get very little sleep and people who get lots of sleep are more likely to die early than people who average around 7-8 hours a night,” explains Dr Morgan. “But really heavy sleepers have the highest mortality of all, possibly because it shows an underlying metabolic problem.”
8. The richer you are the better you sleep
A Sleep Council study found that people who earned more slept better than those who earned less or were unemployed. High earners (£65 – £75,000) get the best sleep of all.
This doesn’t come as a surprise to Professor Sara Arber, professor of sociology at the University of Surrey who has looked into the link between affluence and sleep patterns. “People who are jobless or on low incomes are likely to have stresses and worries, which can cause sleep disturbance. Also, your physical environment can affect your sleep. If you have to sleep on a sofa or live in a high rise with paper thin walls, you are more likely to be disturbed at night than if you live in a detached house in a leafy suburb.”
Chris Idziwoski points out that affluent people tend to adopt healthier lifestyles and diets and both of these contribute to good sleep.
9. New mums and post-natal insomnia
Most new mums have to put up with interrupted sleep. Recent research has shown that new mothers spend around 20% more time awake during the first six weeks after childbirth than is the average. But a few women who have recently given birth suffer from post natal insomnia, when they can’t fall back to sleep after midnight feeds. Midwife adviser Janet Fyle explains: “If lack of sleep becomes constant it can lead to postnatal depression.
Most women are able to return to their usual sleep patterns once their baby begins to adjust and can sleep through the whole night, though for others the mixture of psychological and physical changes and the shell shock of becoming a mother, can lead to this problem becoming a habit.
10. Junk sleep instead of teen dreams
According to research, almost a quarter of teenagers fall asleep with the TV or laptop computer on, their ipod still playing their favourite tunes or some kind of electrical gadget still running more than once a week. The Sleep Council says that this behaviour is fuelling a rise in poor quality ‘junk sleep’. Dr Chris Idzikowski is dismayed by the findings. “This is an incredibly worrying trend,” he says.
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