Most people know that adequate sleep is one of the cornerstones of good health. But is poor sleep bad for your waistline?
It’s not as flashy as diet products like Garcinia Cambogia, but adequate sleep is important for weight loss.
A recent meta-analysis examined the association of sleep quality and overweight and obesity in young people. Here is a detailed summary of its findings.
As opposed to sleep duration, sleep quality is more about the personal experience of sleep, such as difficulties falling asleep or sleep satisfaction. Broken sleep is also an aspect of sleep quality (6).
Some observational studies indicate that light pollution at night might increase weight by disrupting sleep.
However, until now, no meta-analyses have examined the association of sleep quality and overweight or obesity.
This was a systematic review and meta-analysis on the association of sleep quality and overweight and obesity.
This was a systematic review and meta-analysis of observational studies.
Its purpose was to examine the association of sleep quality and overweight and obesity in young people and find out if the association is independent of sleep duration.
The researchers selected nine observational studies for the meta-analysis, including a total of 26,553 children, adolescents and young adults.
Most of the included studies had a cross-sectional design, meaning that they examined the association at one point in time. In other words, they didn’t investigate the effect of poor quality sleep on weight changes over time.
Studies were excluded if they didn’t include body mass index as an outcome or the participants had medical or psychological problems.
Additionally, studies were left out if they only focused on sleep duration or all of the participants were overweight or obese.
Poor sleep quality was defined as difficulties falling asleep and sleep disturbances (recurrent awakenings).
Some of the studies assessed sleep using the Pittsburgh Sleep Quality Index or the Children’s Sleep Habits Questionnaire, both of which evaluate sleep duration and quality.
Bottom Line: This was a systematic review and meta-analysis of studies examining the association of sleep quality and overweight or obesity.
Finding: Poor Sleep Quality Was Associated With Overweight and Obesity
This meta-analysis suggests that both short sleep duration and poor sleep quality makes young people more likely to be overweight or obese.
Most of the included studies found that inadequate sleep was significantly associated with overweight and obesity.
Most of the included studies were cross-sectional, measuring associations at one point in time. In contrast, only two of the studies were longitudinal, measuring sleep quality and changes in weight over time.
Bottom Line: The study suggests that poor sleep quality is associated with overweight and obesity in young people, independently of sleep duration.
How Could Low Sleep Quality Make People Fat?
Although this study didn’t prove that poor sleep quality may lead to fat gain, it seems plausible that it might.
The potential mechanisms are unclear, but scientists have a few ideas.
- Disrupted body clock: The body’s timekeeping system regulates many aspects of metabolism. Disrupting this system by sleeping irregularly or poorly may increase weight gain. (12, 13).
- Increased appetite: Irregular or low-quality sleep can disrupt the 24-hour fluctuations in appetite hormones, promoting increased calorie intake during the day and at night (14).
- Food intake at night: Broken sleep or difficulties falling asleep may encourage night-time eating, leading to more weight gain.
Bottom Line: Several plausible ideas explain how poor sleep might promote weight gain. For example, low sleep quality may disrupt the body clock and encourage night-time snacking.
This study had a few important limitations.
First, all of the included studies had an observational design, and all but three were cross-sectional. This means that they couldn’t prove causality and didn’t show that poor sleep was linked with weight gain over time.
It’s plausible that being overweight or obese may reduce sleep quality, rather than the other way around.
Second, only three studies measured sleep quality, using actigraphy. Additionally, most of the included studies used validated questionnaires, whereas three relied on parental or self-reporting.
Finally, most of the studies used body mass index (BMI) as an outcome. Four of the studies used self-reported height and weight for calculating BMI. BMI is an inaccurate measure of overweight, especially when relying on self-reports.
Bottom Line: The meta-analysis included observational studies, which cannot prove a causal relationship. Additionally, most of the studies relied on inaccurate measurements.
Summary and Real-Life Application
In short, this study indicates that poor sleep quality — broken sleep or difficulties falling asleep — are associated with excessive fat mass.
However, the evidence is weak, and the direction of causality is unclear. Obesity, overweight or related factors are plausibly responsible for poor sleep quality, at least in some cases.
Regardless, there is no doubt that getting high-quality sleep is important for maintaining a healthy mind and body.