Sleep and Obesity: The Role of Sleep in Weight Management

Hello everyone. My name is Laura Perada. I am an assistant professor in dermatology at Harvard Medical School and I work as a clinical researcher at the Brigham and Women's Hospital in the department of dermatology. And today I'm going to be talking about sleep and obesity, the role of sleep in weight management.

So today I would like to discuss an increasingly recognized component of weight regulation and cardiometabolic health that is typically not so discussed and people are not so aware of, which is sleep. We traditionally approach obesity management through nutrition, physical activity and pharmacological interventions. However, sleep is another potentially modifiable behavior that deserves consideration. And for our patients with rheumatologic conditions, this is particularly relevant given the frequent coexistence of sleep disturbance, pain, fatigue and increased cardiometabolic risk.

Starting with epidemiological studies, there is evidence that short sleep duration, which is generally defined as less than six hours per night, has been associated in a study with 8% higher relative risk of central obesity. Importantly, this association in this study was persistent even in studies that had excluded BMI in their adjustment models. Although these findings cannot establish causality between these associations, they do suggest that insufficient sleep may be relevant not only to overall body weight but also to abdominal adiposity.

Experimental studies build on these findings. So in a randomized controlled crossover study, healthy adults who were restricted to 4 hours of sleep per night for two weeks showed to have consumed approximately 300 more calories compared to the control group who had adequate sleep duration, and that this addition in calories per day was also happening in the context of increased energy expenditure. But perhaps the most interesting finding of this study was that there was also an 11% increase in visceral fat, which was measured using abdominal CT. So this suggests that insufficient sleep may influence not only weight gain but potentially also where fat excess is accumulating, which has important implications for cardiometabolic health.

One limitation of these experiments however is that they involved fairly extreme sleep restrictions, as I mentioned before, of 4 hours per night for 2 weeks. So there were other studies in which they modified sleep but more on the moderate side. So there's a particular study by Sur Kat and colleagues in which they examined a more moderate sustained sleep insufficiency including 95 adults. So what they did was they reduced the sleep of these individuals by 78 minutes for 6 weeks and they observed that this resulted in greater body weight, increased waist circumference and also more sedentary time. Interestingly, hormones such as leptin increased alongside this weight gain, but then there were others such as ghrelin and GLP-1s that remained statistically unchanged. So these findings suggest that even modest chronic sleep insufficiency can adversely affect weight regulation through mechanisms that are more complex than we anticipated.

Then it is also important to note that the metabolic consequences of poor sleep extend beyond weight gain and energy intake. In a recent systematic review of randomized trials, they found that sleep restriction also negatively affects insulin sensitivity. Importantly, these effects were not limited to sleep duration. They also observed adverse outcomes with circadian misalignment and a suppression of slow wave sleep. So this put together reinforces the importance of considering sleep health as a multi-dimensional construct, and not only that sleep duration is the sleep domain that is associated with these adverse cardiometabolic outcomes.

And so why does insufficient sleep influence eating behavior? Traditionally we thought that increased hunger was happening through changes in ghrelin and leptin exclusively. However, in a recent review it was shown that increased hunger does not always translate into increased food intake and that people may also eat more without feeling hungrier. So the mechanisms underlying these associations still remain unclear and there seems to be a place also for behaviors such as food reward and the opportunity to eat more when sleep is more restricted that may be playing a role too.

And all this data that I just shared with you then raises an important question. If restricting sleep promotes weight gain, can extending sleep have the opposite effect? So Tasali and colleagues tried to address this question through a randomized trial in which they examined 80 adults with overweight who habitually slept less than 6 and a half hours per night. And following individualized counseling, participants slept 1.2 hours longer
per night and consumed approximately 270 fewer calories per day compared with controls. So, and this was without changing their diet or their physical activity. So, this ultimately resulted in a modest short-term weight reduction. And these studies were further complemented by other studies that showed that behavioral sleep interventions reduced caloric intake by approximately 150 calories with some improvements also in weight and BMI particularly among people who were obese.

However, we should say that overall the results are inconsistent and that long-term studies are still necessary to determine these associations. So, what does this mean for our clinical practice there? I think that there are three main messages that I would like to share with you today. The first is that sleep deserves consideration when discussing obesity and cardiometabolic health including not only sleep duration but also other domains of sleep such as sleep quality, timing, regularity. Second, that insufficient sleep may contribute to adverse metabolic outcomes through several interconnected pathways, including increased energy intake, changes in adiposity, and impaired insulin sensitivity. And finally, that improving sleep may support existing weight management strategies, although it should not be considered as a standalone treatment for obesity, and more evidence is needed to truly demonstrate this positive effect.

So with that I'm going to conclude this talk on obesity and sleep and I hope that this information was useful and interesting to you and if you have additional questions about this topic please refer to the RheumNow website for additional details. Thank you.