It might not just be junk food making you fat – your sleeping habits could also be to blame

Could the obesity epidemic be all down to poor sleep? Experts believe a good night’s shut-eye is as important a factor as any other in ensuring people control their weight and waistlines.

Disrupted sleep patterns are a common feature of modern living and can trigger changes in appetite, metabolism, motivation and physical activity causing disruption of people’s eating habits and, eventually, weight gain.

Christian Benedict, a neuroscientist at Uppsala University in Sweden, says: “Our studies suggest that sleep loss favours weight gain in humans.

“It is therefore fair to say that improving sleep could be a promising lifestyle intervention to reduce the risk of future weight gain.”

Two-thirds of people in Europe are now considered overweight, while a quarter are reckoned to be obese and in real danger of dying prematurely.

Lack of exercise is clearly involved, so is cheap processed food and sugary drinks. But sleep is also a factor, says Benedict, particularly in our 24/7 culture where more people are reporting problems getting quality sleep – and where studies have increasingly pointed to a higher correlation between sleep deprivation and weight gain.

In one experiment carried out by the Uppsala team, a group of 14 male students were put through a series of sleep experiences ranging from normal sleep to curtailed sleep to no sleep at all over several days.

The students were then measured for changes to how much they ate, their blood sugar and hormone levels and their metabolic rate. The results were striking.

Even a single night of missed sleep was found to slow a person’s metabolism the next day, reducing energy expenditure for tasks such as breathing and digestion by between 5% and 20%.

The students also had higher levels of blood sugar, appetite-regulating hormones such as ghrelin, and stress hormones like cortisol after sleep disruption.

The sleep loss did not, however, boost the amount of food consumed during the day, though it had other effects on eating.

Benedict says: “Sleep-deprived people prefer larger food portions, seek more calories and eat impulsively. Sleep loss shifts the hormonal balance from those which promote fullness to those that promote hunger, such as ghrelin.

“As a result, people think they are hungrier than they really are.”

Further work from Benedict’s team has also shown that acute sleep loss alters the balance of gut bacteria, hampering the immune system and reducing sensitivity to insulin, which in itself leads to obesity and type 2 diabetes.