London - A lack of sleep not only increases tiredness and irritability - it can also expand your waistline.
After being deprived of one night's rest, participants in a study went on to purchase food that was higher in calories and weighed almost a fifth more than their normal shop.
Scientists from Uppsala University in Sweden found that poor or no sleep resulted in raised levels of a hormone that is linked to boosting hunger.
In the tests, adults who spent an entire night with no sleep were given a selection of 40 food items the following morning.
They bought food with nine percent more calories compared to mornings when they had a night's sleep.
Shopping while tired could have a knock-on effect for our overall wellbeing, the researchers warned, as individuals will often purchase several meals during one trip.
“We hypothesised that sleep deprivation's impact on hunger and decision making would make for the 'perfect storm' with regard to shopping and food purchasing-leaving individuals hungrier and less capable of employing self-control and higher-level decision-making processes to avoid making impulsive, calorie-driven purchases,” said lead author Colin Chapman from Uppsala University.
The study, published in the journal Obesity, examined 14 men who were of normal weight.
After one night of total sleep deprivation, they were given a fixed budget of around £30 (about R450) to spend on a display of foods that included 20 high-calorie and 20 low-calorie options. The experiment was also repeated after they had enjoyed a good night's rest.
Before the task, participants received breakfast to minimise the effect of hunger on their purchases.
Despite having a full stomach, sleep-deprived men purchased food with nine percent higher calories and weighing 18 percent more than they did after one night of sleep.
“Our finding provides a strong rationale for suggesting that patients with concerns regarding caloric intake and weight gain maintain a healthy, normal sleep schedule,” said Chapman.
The report concluded: “Our findings demonstrate that participants purchased significantly more calories and grams of food, within the same budget, following sleep deprivation.
“This is significant as the stocks that one purchases last beyond the acute sleep deprivation, and will influence food consumption choices long after the purchases are made.'“
They warned their findings could be relevant to shift workers who often lose out on sleep, such as taxi drivers and health workers.
A study earlier this year found that women who work night shifts can find it 80 percent harder to have a baby.
Any erratic work pattern carries higher risk of miscarriage, irregular periods and fertility problems compared to a nine to five routine, research by Southampton University suggests.
Shift workers are twice as likely to be classed sub-fertile - meaning they fail to get pregnant within a year.
LACK OF SLEEP MAKES PEOPLE UNATTRACTIVE
Researchers at the University of Stockholm found that people think sleep deprived individuals look, sad, unattractive and unhealthy.
The researchers believe that these perceptions could influence the way in which people treat those who are sleep deprived.
They photographed people on two occasions – once after a good night’s sleep, and once after they had been awake for 31 hours.
The team then asked 40 people to rate the pictures on how tired, sad and attractive the subjects looked.
They discovered that people’s eyes take the heaviest toll from sleep deprivation and that they become redder and more swollen. - Daily Mail