Around 60 per cent of British adults are overweight or obese, and research suggests that the cause may not be overeating or lack of exercise, but sleep deprivation.
‘We have done a series of studies looking at weight and sleep, and studying the metabolic rate,’ says Dr Shahrad Taheri, a consultant endocrinologist at Birmingham Heartlands Hospital.
It also seems that people who sleep for fewer than four hours a night are 73 per cent more likely to gain excess weight, while restricting sleep can lead to cravings for up to 900 extra calories a day.
This much food on top of a normal diet could result in an alarming weight gain of up to 2lb a week.
The findings suggested that although participants had no significant weight problems beforehand, their weight grew as their sleeping time shrank.
‘Lack of sleep seems to stimulate the hormones that regulate appetite,’ explains Dr Taheri. ‘It leads to higher levels of ghrelin, a hormone that triggers appetite, and lower levels of leptin, that tells your body it’s full.’
And the problem is set to increase. In the past 50 years, the average night’s sleep has dropped from nine to seven hours.
And a new survey by the Vitality Show reveals that just 19 per cent of adults enjoy a full eight hours a night, while 16 per cent are getting by on fewer than six.
Over half of us are regularly so weary at work that we long to go home, while 59 per cent of women in their 30s are ‘tired all the time’.
Forget Broken Britain, this is Broken Night Britain - and while the occasional late bedtime can be slept off, our chronic levels of sleep deprivation are pushing us beyond mere tiredness into ill-health, with an increased risk of diabetes and heart disease.
Sleep is a feminist issueWhile there is plenty of evidence to support the idea that restricted sleep leads to haywire hormones, Dr Taheri’s team is investigating other factors in the connection between insomnia and weight gain.
‘The longer you’re awake, the more time there is to eat, for instance,’ he adds. ‘And obesity is likely to lead to broken sleep. Weight is a factor in sleep apnoea [a sudden halt in breathing patterns] and snoring, which are more likely to wake you during the night, so you can end up in a vicious cycle.’
Other studies have found that lack of sleep can double the risk of obesity in adults.
‘I’ve never been a good sleeper and have always struggled with my weight,’ says 32-year-old Claudia Phillips, from Surrey. ‘In my 20s, I started being unable to sleep for more than an hour at a time. My GP thought the stress of my job may have been a factor and he prescribed sleeping pills. But he also believed the insomnia and weight gain could be linked as, without sleep, the body does not metabolise food effectively.’
In an informal experiment by a U.S. magazine, led by Dr Michael Breus, a group of women were asked to keep their eating and exercise habits as they were, but to sleep for seven-and-a-half hours a night.
Astonishingly, all the women lost between 3lb and 15lb. Now, a larger U.S. study is investigating the effect that sleeping for longer has on body weight. ‘We are looking at the prevention of obesity,’ Dr Taheri says. ‘The connection [between sleep deprivation and putting on weight] holds true everywhere, even Japan.’
Dr Taheri recommends between seven and eight hours of uninterrupted sleep a night.
‘You can find out your natural sleep rhythm on holiday,’ he says. ‘For the first few days you’re catching up on your sleep debt, but after that you’ll start to wake naturally, when your body feels it’s had enough.’
In 2009, the NHS spent £36million on sleeping pills, a 20 per cent rise from the previous year
It seems simple enough, but the pressures of modern life often combine to push bedtime further back. A third of us are so stressed about work that we can’t sleep, while alcohol dramatically increases the chances of broken sleep.
And while old-fashioned advice recommended that new parents ‘sleep when baby sleeps’, that’s not possible for working mums with a 6am start.
So should we be swapping counting calories for counting sheep? Dr Taheri thinks so.
‘We recommend no caffeine after 6pm, no exercise before bed, avoiding excess alcohol - and we’ve even discovered a link between watching TV in bed and obesity, because it increases the chance of disrupted sleep,’ he says.
If lifestyle factors are to blame, it’s possible dramatically to increase your chances of a good night’s sleep by following Dr Taheri’s advice. But for the 10 per cent of adults who suffer long-term, chronic insomnia, therapy can succeed where camomile tea does not.
Claudia finally cracked her problem by splashing out on a new bed, taking up yoga, and ditching the sleeping pills. She says she’s sleeping better - and losing her excess pounds.
But many women find it much more difficult to get the sleep they so desperately need. Living at breakneck speed can mean you regularly end up sharing your bed with a tetchy child, a beeping BlackBerry and, most likely, a snoring partner.
‘Male snoring is a big problem,’ agrees Jim Horne, director of the Sleep Research Centre at Loughborough University. ‘During the night, the man disturbs the woman, much more than the other way round. Because women tend to be lighter, sleep disturbance is also often caused by her partner shifting in the bed - she’s literally propelled around it by his weight.’
Back-up plan: If camomile tea doesn't work, therapy may resolve anxieties that keep the brain wired at night
Generally, women also sleep more lightly than men - which may, according to Dr Horne, be due to motherhood. ‘Women with children are extremely sensitive to the sound of their child crying,’ he says. ‘They’ll wake at the slightest noise.’
Hormonal issues, such as pregnancy and the menopause, can also affect sleep hormones - and once we do wake up, we find it much harder to get back to sleep.
‘I always slept well until the menopause,’ says Liz Peterson, 59, from Chichester.
‘Now, I never get a full night’s sleep without taking sleeping pills, which I don’t like doing, but I’ve tried everything else and it just doesn’t work.’
Liz has a demanding job in the hospitality industry and explains: ‘I can’t get through the day if I’m tired - it’s impossible to function. But every night, for years, I’ve woken up at 4am then can’t get back to sleep.’
She also believes her insomnia could be stress-related. ‘When I go on holiday, I have
no problem sleeping. But though I’m not under any enormous stress at home, there I’ll wake up, start worrying and then I’ll be awake for hours.’
Liz reports that many of her female friends are the same: ‘For many of them, it started around the menopause, and we all feel it’s just something we have to put up with.
Liz has tried all the advice on bedtime routine, including hot drinks and calming colours in the bedroom, but nothing has worked. So now, she’s now resigned to a lifetime of tiredness. ‘My GP prescribed the sleeping pills, and until science finds something else, I just reluctantly accept that I’m going to have to keep taking them,’ she says.
But while in extreme cases sleep experts may prescribe melatonin, a hormone that regulates circadian rhythms (a roughly 24-hour cycle of our biochemical, physiological and behavioural processes), Dr Horne believes that there could be a simpler solution.
‘Most people don’t realise that a 15-minute nap in the afternoon is equivalent to an extra hour’s sleep in the morning,’ he says.
‘Good sleep is about the quality and timing, rather than quantity. But don’t be tempted to take more than 15 minutes, or you’ll wake up feeling-groggy.’ With our weight creeping up as our sleeping hours shrink, perhaps we’ve stumbled on the missing link. If it’s really possible to drop a dress size while you sleep, that’s got to be worth a few early nights.