When it comes to controlling our weight, a lot of time and effort is spent trying to improve our diets and exercise regime.
But a new University of Otago study suggests we should look at how much sleep we are getting instead.
The study, led by department of medicine PhD candidates Rosie Jackson and Silke Morrison, showed small changes in children’s sleep — as little as 40 minutes less a night — could negatively affect their eating habits.
If children were sleep-deprived, they tended to boost their energy after 5pm by eating non-core, highly processed foods such as cakes, biscuits and chips.
The study involved 100 Dunedin children, aged 8-12.
Their bedtime was brought forward by one hour for one week, and pushed back an hour for another week (with one week between), and their sleep, dietary intake and desire to eat different foods was measured.
Ms Jackson said the children ate considerably more energy foods when they were sleep deprived.
Parents of the participants also reported that their child seemed to eat both more and less in response to their emotions when they were tired, and they also felt they parented slightly differently around food when their child had less sleep.
"It may be that during sleep restriction, children showed emotional undereating when offered less desirable, healthier foods — which are often lower in energy — yet exhibited emotional overeating when around highly palatable energy-dense foods, often consumed by people who are considered emotional overeaters."
She said the difference in calorie intake (the equivalent of about two to three biscuits a day) was clinically significant and could result in excess weight over time if not counter-balanced by increased energy output.
"Although this seems small at the individual level, if a child ate this in excess every day, it would be enough to explain several kilos of extra weight per year — and therefore, enough to explain the link between not getting enough sleep and higher body weight.
"You only need a small difference in energy intake and expenditure each day to lead to weight gain over time."
Eating behaviours were thought to develop early in life and remain through childhood.
However, the study suggested that sleep may be one factor that could influence eating behaviours in children, she said.
“It could be as simple as just having more time in the day to eat, but our data also show that food and emotions are tied together when thinking about sleep in children.
"Getting a good night’s sleep is important for so many aspects of our lives, including what and how we eat."
