In a fascinating study by researchers at Pennsylvania State University, sleep restriction was once again shown to have remarkably negative affect on humans. In this case, only a few days of sleep restriction affected how full participants felt after eating, along with altering fat metabolism. A full night of recovery sleep wasn’t enough to reverse the effects.
If you work for a living, raise a family or pretty much do anything resembling interacting in the world, you’ve probably been a little short on sleep at one point or another in your life. It’s likely that lack of sleep is harming you. This study, published in the Journal of Lipid Research, reinforces the huge body of evidence that says exactly that.
Orfeu Buxton is a professor at Penn State University and a senior author of this study. He’s also the guy who contributed to a lot of the research showing that long-term sleep restriction, disruption and deprivation increases the risk of obesity and diabetes for humans. He points out, however, that the majority of research has looked at glucose metabolism. While this is important to understanding the relationship between sleep problems and diabetes, it’s not the whole problem. Lipid digestion and metabolism are crucial for preventing obesity and it’s related diseases and conditions.
For this study, 15 healthy, 20-something men were permitted to get a week of ample sleep at home before checking in to the Penn State University sleep lab for a 10 night study. Researchers re-created a restricted-sleep schedule similar to that kept by far too many Americans who work for a living or raise a family. Five of the ten men followed that pattern, getting no more than 5 hours per night for 5 of the nights.
Kelly Ness, who ran the study, noted that researchers not only observed the men and collected data, but also spent time “interacting with the subjects, playing games with them, talking with them — helping to keep them awake and engaged and positive.”
In order to detect changes in metabolism, especially fat metabolism, from the altered sleep schedule, participants consumed a standardized high-fat dinner after having endured 4 nights of sleep restriction. “It was very palatable — none of our subjects had trouble finishing it — but very calorically dense,” Ness said of the chili mac dinner. Notable was the fact that most participants felt less satisfied after eating this meal when they were sleep-deprived than they reported after consuming it when well-rested.
The research team then took blood samples from each “sleep” group. They compared the postprandial lipid response, or rate of fat clearing from the bloodstream after a meal, of the sleep-deprived group against that of the rested group. Sleep restriction impacted the response by leading to faster clearance of lipids from the blood after a meal.
This, researchers believe, can predispose sleep-deprived people to put on weight. “The lipids weren’t evaporating — they were being stored,” Buxton explained.
Participants were given a simulated weekend at the end of the simulated 5 day work week. This allowed them to get a solid 10 hours sleep to catch up on needed rest. After the first recovery night, they were again served the chili mac meal. Postprandial lipid response improved, but didn’t approach a baseline healthy level.
Researchers admit that the study is an imperfect model for life and lipid metabolism in the real world, since it was tightly controlled. All the “sleepers” were male, young and healthy, thereby at a lower risk of cardiovascular disease.
One question left unanswered for researchers is whether more recovery time would change the degree to which lipid response recovered. The natural follow-up question is one involving the amount of time needed to recover to a healthy baseline postprandial lipid response rate.
Buxton still believes the study provides worthwhile insight into how the human body handles fat digestion – and what might disrupt it, as well as to what degree. “This study’s importance relies on its translational relevance. A high-fat meal in the evening, at dinnertime — and real food, not something infused into the vein? That’s a typical exposure. That’s very American.”
Combine the American diet with typical American sleep patterns and what do you get? If Buxton and his team are right, you get fatter and less healthy Americans.
Keep the faith and keep after it!