Lack of sleep often signals the body that we are dealing with a problem, and in response metabolism slows down, which encourages us to eat more than we need so we have enough energy to cope with the problem.
“While this was a good mechanism in evolutionary terms, to store energy for tough times, it’s not so good in today’s developed world where we are relatively inactive and calorie-dense foods are easy to come by cheaply and without physical effort,” explains senior author professor Orfeu Buxton.
15 men in their 20s spent ten nights of getting plenty of sleep at home, and then spent 10 nights sleeping in a sleep lab; during 4 consecutive nights in the lab they only slept 5 hours, and were fed a high fat, high calorie pasta and chili diet while in lab. Blood samples taken while the subjects were eating revealed lack of sleep led to increased insulin levels and faster lipid clearance from blood; changes make it easier to gain weight as the lipid were being stored not disappearing.
“Most of the participants reported they felt less satisfied after eating the same meal while sleep-deprived, than when they had eaten it well-rested,” comments Kelly Ness, a postdoctoral fellow at the University of Washington. Ness ran the experiment while she was a graduate student at Penn State. “Across a lifetime of exposure to short sleep, this could increase the risk of obesity, diabetes or other metabolic diseases,” Ness adds.
Having participants sleep for 10 hours on 2 consecutive days was intended to simulate catching up on sleep over a weekend; metabolic processing of fat was slightly faster after getting more sleep, and weight returned to normal, but metabolism failed to return to baseline readings. Findings suggest that complex metabolic shifts occurs after a period of restricted sleep which is not understood yet.
“The primary problem in obesity is how fat tissue functions to store fat energy,” says associate professor Greg Shearer. “By storing fats quickly, fat tissues appear to shift fuel utilization away from fats and prioritize the use of sugars for fuel. Here we show evidence that sleep restriction exaggerates this process, conserving energy stores.”
As published in The Journal of Lipid Research in future experiments the team hope to include a broader experimental population and allow for extended recovery periods.
