Have trouble staying awake? Try dieting — less food ‘raises alertness and improves sleep’

Weight loss brought on by a change in diet can improve sleep, according to a study by researchers from the University of Pennsylvania.

The study, published this month in the journal Sleep, offers new insights into how weight fluctuations affect sleep regardless of your body weight.

Previous studies have linked obesity with fatigue and lack of energy. But this is the first research of its kind to establish the link between excessive weight, poor dietary habits, and sleep abnormalities.

The researchers studied obesity in mice fed on a high-fat diet for eight weeks. After that period, some of the test subjects were switched to a more balanced diet. After the ninth week, mice maintained on the high-fat diet weighed 30 per cent more, slept more than an hour longer a day, and suffered from increased wake fragmentation (frequently slipping into sleep) compared to mice maintained on a healthy diet.

The study’s lead author, Isaac Perron, said: ‘Our findings suggest body weight is a less important factor than changes in weight for regulating sleepiness. Diet-induced obese mice that ate a regular chow diet for only one week showed the same sleep/wake profile as mice that ate a regular chow diet for nine weeks.’

The researchers also found that just one week on a high-fat diet caused previously healthy mice to suffer from the same sleep problems as those on a long-term high-fat diet.

Perron said: ‘The diet consumed during the final week was key to driving the sleep effects, independent of the starting body weight. If you’re overweight and often feel tired, you may not need to lose all the weight to improve sleep, but rather just beginning to lose that excess weight may improve your sleep abnormalities and wake impairments.’

The study’s co-author, Sigrid Veasey, a professor specialising in sleep medicine, said: ‘This study has mapped a completely novel food and sleep interaction. That changing to a healthier diet can acutely improve alertness and sleep, is extremely important and certainly an interaction to now test in humans.’

In England, 62.7 per cent of adults are overweight or obese. Poor sleep is also associated with conditions such as depression, obesity, and hypertension.