How Sleep Loss Affects Energy Intake 😴
Hey guys! So, as I’m sure you are well aware, Daylight Saving Time kicks in tomorrow here in the US. This one hour shift throws most of us into a state of circadian misalignment, and of course means we lose an hour of sleep. Fortunately, this is generally a transient issue, as our biological clocks eventually recalibrate to the new time.
A much bigger problem is the chronic and pervasive reduction in overall sleep that we see in modern society, which is notably accompanied by a doubling of the global prevalence of obesity. The timing of these trends is probably not merely coincidental, as growing research shows that sleep deprivation has a significant impact on appetite and energy intake. Specifically, sleep loss seems to affect how the body regulates certain neurotransmitters that affect hunger and satiety. It also seems to affect food preferences, making sleepy individuals favor sugary “comfort food.”
So, how big of a difference does this make? How much sleep do you need to keep your appetite reined in at a healthy level? And does this mean that intentionally getting more sleep could actually help people lose weight?
To learn more, scroll on down 👇🏻
This Week's Research Highlights
🥱 Inadequate sleep has been shown to be associated with obesity in multiple observational studies.
A number of cross-sectional studies have shown a link between reduced sleep and increased weight. For instance, when researchers analyzed data from representative sample of American adults (NHANES), they found that people who slept less than 7 hours per night were 1.83 times more likely to be overweight and 1.57 times more likely to be obese, compared to those who slept 7-9 hours nightly. However, it is worth noting that this type of study is pretty limited, because it is only looking at data at a single point in time. It’s hard to see how sleep actually affects weight with that design. More rigorous longitudinal studies, which follow subjects for a longer period of time and take repeated measurements (that way you can see if changes in sleep result in changes in weight) do seem to support the link as well though. When researchers followed a cohort who was free of obesity at the start of the study for six years, they found that every hour increase in total sleep time per night was associated with 30% reduced odds of going on to develop obesity.
⏰ Sleep duration is associated with shifts in hormones linked to appetite.
Researchers in Chicago had 12 healthy young men undergo two days of sleep restriction (4 hours in bed) and two days of sleep extension (10 hours in bed), and obtained numerous blood samples during both conditions. The sleep curtailment resulted in an 18% reduction in leptin, a hormone secreted from fat cells that tends to inhibit hunger. To put that into perspective, 3 days of eating only 900 calories per day in lean volunteers has been shown to lead to a decrease in leptin of 22%. The sleep loss also led to a 28% increase in ghrelin, a hormone secreted from the gut that increases the drive to eat. Unsurprisingly, these reciprocal alterations in hormones that govern appetite led to significantly greater self-reported hunger in these men, especially for calorie dense snacks. The increased hunger was closely correlated with increased ghrelin-to-leptin ratio.
🍟 Restricting sleep increases subsequent energy intake.
Twelve healthy young men spent the night at the lab on two separate occasions, differing only in the amount of sleep they were permitted. On one night, they got only four hours of sleep, and on the other they got a full eight hours. Then, on the following day of each lab visit, they were presented with as much food as they wanted (including a lunch buffet and a free menu for dinner, which sounds kind of awesome). Compared to when they got eight hours of sleep, the subjects consumed 22% more calories on average (559 +/- 617 calories) after the night of sleep restriction.
⚖️ Increasing sleep duration lowers energy intake and results in negative energy balance.
Researchers recruited 80 overweight young adults (BMI between 25 to 29.9) and randomly assigned them to either two weeks of sleep extension (using personalized sleep hygiene counseling) or two weeks of continued sleep as usual. Energy expenditure was measured using doubly labeled water, and they were able to objectively monitor changes in body mass using DEXA. The sleep intervention was pretty effective, resulting in an overall increase in objective sleep duration of around 1.2 hours in subjects who normally slept less than 6.5 hours per night. But even more impressively, the sleep extension group showed an average decrease in energy intake of 270 calories per day, which in turn led to weight loss in that group.
Random Trivia & Weird News
🦘 There is a recognized phenomenon known as “phantom kangaroo,” in which the marsupials are reported in areas where they are not native.
Podcasts We Loved This Week
- Danny Lennon, Alan Flanagan, & Niamh Aspell: Food environments. Via Sigma Nutrition Radio.
- Laurie Winkless: The science behind why some things are sticky and some things are slippery. Via Science Friday.
Products We Are Enjoying
Sleep mask
One thing that can help you adjust to time changes is to achieve total darkness when you want to go to sleep. Of course, we don’t always have that environment at our disposal, which is where sleep masks can be helpful.
I like this one because it is super soft and fully adjustable, ensuring a comfortable fit without pressing too hard on your face or your eyeballs. It’s also huge, like almost ridiculously big, so it can block out all light even if you are wearing it loosely (or if you have a big face). Plenty of color options too!
humanOS Catalog Feature of the Week
Sleep and Weight Control
This week, we’d like to highlight one of the courses from the Ideal Weight Program, developed by Stephan Guyenet. Much of the Ideal Weight Program is centered around nutrition, as you would expect, but research has shown that multiple aspects of our lifestyle play an important role in body weight. Sleep is one of the most important, and perhaps most underappreciated.
In this course, Stephan reviews the basics of sleep and circadian rhythms, then zooms in on how insufficient or misaligned sleep specifically influences body fatness. He looks at a few key studies that have examined the impact of altered sleep on food intake, which largely mirror the findings that we described above. But it actually gets even worse - sleep loss can also adversely affect nutrient partitioning, making it harder for you to hold onto muscle! Fortunately, this is for the most part a solvable problem. Stephan covers realistic ways for you to obtain restorative sleep, and hopefully achieve your body composition (and health) goals.
Thanks for reading! If you're looking for more juicy health research (and occasionally random science or memes), be sure to visit with us on Twitter on @humanOS_me.
