If you snooze, you just might lose (weight, that is)

A study conducted at Uppsala University has revealed that sleep-deprived people have greater appetites for energy-dense foodstuffs than those who have had sufficient amounts of sleep. The authors, whose findings have been published in the journal Psychoneuroendocrinology, conclude that poor sleep habits could increase an individual’s risk of becoming overweight.

In a previous paper, published in the Journal of Clinical Endocrinology & Metabolism, the team demonstrated that if a young man of normal weight loses just one night of sleep, the region of his brain connected with the desire to eat will exhibit higher levels of activation. In their latest study, the researchers investigated whether or not sleep-deprived individuals are prone to selecting larger portions within a buffet situation.

To find out more about fatigue’s potential to increase one’s desire for calorific consumption, I spoke to lead researcher Dr Pleunie Hogenkamp from Uppsala’s Department of Neuroscience. I began by asking whether she and her colleagues were surprised by the extent to which sleep-deprived participants tended to opt for larger portions of high-energy foods.

"We were not overly surprised by the difference in their selected portion sizes," she explained. "We expected to find a discrepancy between the appetites of those who had slept well and those who had not. However, we were surprised to find a clear differentiation between the two groups after they had eaten breakfast. Even when sleep-deprived participants were satiated, they still opted for larger, higher-calorie meals than their rested counterparts. We did not expect this to be the case after breakfast."

Dr Hogenkamp and her colleagues asked 16 males of normal weight to choose their ideal portion sizes from a selection of seven meals and six snacks, once when they had slept for eight hours the night before and once when they had been deprived of sleep. Both before and after they had eaten breakfast, fatigued males tended to select larger portions of energy-dense food. I asked how much the researchers understood about why sleep deprivation appears to increase appetite regardless of a person’s level of hunger.

"Well of course, this is the question that we would like to answer," Dr Hogenkamp replied. "Previous studies have demonstrated that after sleep deprivation, our brain’s responses to food are similar to those exhibited by obese patients. We suspect that after sleep loss, the reward centres of the brain become more sensitive to food-based stimuli. If true, this could explain why fatigued people have greater appetites even when they have already eaten."

I went on to ask whether it was the quantity or quality of a person’s sleep that had the greatest potential to impact his or her appetite. As Dr Hogenkamp explained, the two are intrinsically linked.

"Quality of sleep definitely plays a role, but then it is closely connected with the amount of sleep that a person gets," she said. "Most research literature in this area points to the fact that the longer you sleep, the better the quality of your sleep is likely to be."

In light of their findings, the researchers contend that poor habits might increase an individual’s risk of becoming overweight. Too little sleep could lead to the consumption of too many calories. I asked Dr Hogenkamp whether the same principle might hold in the opposite direction. Could a better sleep regime help those trying to lose weight?

"Yes, that may be the case," she answered. "It would be nice to conduct a follow-up study to find out whether longer periods of sleep promote weight loss amongst dieting patients."

To conclude our conversation, I asked whether the Uppsala-based scientists plan to conduct any further research in this area.

"In addition to the avenues that I have already mentioned, we would like to improve our understanding of the neural circuitry involved in the reward process," answered Dr Hogenkamp. "It would be very interesting to explore the differences between how lean and obese, sleep-deprived individuals respond to food-related stimuli."