The Influence of Body Mass Index on Sleep Apnea and Overall Sleep Quality
Chelsie Rohrscheib, Ph.D. Neuroscientist and Head Sleep Expert, Wesper
Introduction
A recent analysis of hundreds of weekly Wesper users confirmed a strong link between body mass index (BMI), sleep apnea, and sleep quality.
What is BMI?
BMI is a method of measuring body fat based on height and weight. Individuals that fall within a BMI of 18.5-24.9 are considered normal or healthy. Individuals that fall within a BMI of 25-29.9 are considered overweight, individuals that fall within a BMI of 30-34.9 are considered obese, and individuals that fall within a BMI of 35 or greater are considered morbidly obese.
While BMI is not a perfect method for measuring body fat, it is useful for assessing if someone is at risk for sleep apnea. Clinical research has consistently shown that individuals with an overweight or obese BMI are at higher risk for the sleep disorder. More than half of people with obstructive sleep apnea have a BMI in the overweight or obese category [1,2].
What is Sleep Apnea?
Sleep Apnea is a group of breathing-related sleep disorders that result in inconsistent breathing and reduced airflow during sleep. A person with sleep apnea has frequent, long pauses in their breathing that cause a drop in their blood oxygen levels. Sleep apnea is highly disruptive to sleep and raises your risk for many dangerous health conditions like cardiovascular disease and cancer.
Wesper Data Reveals the strong BMI/Sleep Apnea link
A deep dive into the Wesper user data found that 30% of users have a normal BMI, 35% of users have an overweight BMI, and 35% of users have an obese BMI.
To confirm the link between body weight and sleep apnea, the amount of times a Wesper user stopped breathing during sleep and the amount of times their blood oxygen levels dropped was compared to BMI. A person who stops breathing consistently and has frequent drops in their blood oxygen levels is likely to have sleep apnea.
Wesper user data showed that both men and women with an overweight or obese BMI were more likely to have frequent pauses in breathing and drops in blood oxygen consistent with sleep apnea compared to users with a normal BMI.
Next, the study aimed to understand if being even slightly overweight (BMI = 25, 26) carries the same risk for sleep apnea as a higher BMI (27 or greater). It was determined that individuals with a normal BMI 18.5-24.9) have few breathing pauses and are at a low risk for sleep apnea. Interestingly, individuals with a BMI of 25 and 26 have enough pauses in breathing and drops in oxygen to place them at risk for sleep apnea, and have the same level of risk for sleep apnea as someone with a BMI of 27-29. This demonstrates that being even slightly overweight increases a person's developing sleep apnea.
Wesper users within the obese BMI category (BMI = 29.9 or greater) were found to be at the highest risk for sleep apnea. To understand if morbid obesity (BMI = 35 or greater) are at even higher risk for sleep apnea than obese users, the effect of obese and morbid obesity on respiration quality was assessed. Interestingly, obese users had the same risk for sleep apnea as morbidly obese users.
BMI and Snoring
While not all snorers have sleep apnea and not all sleep apnea patients snore, it is one of the most common symptoms of sleep apnea. As with sleep apnea, increased body weight also raises the risk for snoring. To identify if overweight and obese users were more likely to snore, average snoring duration was calculated. Compared to users with a normal BMI, average snoring duration was slightly higher in overweight users, whereas snoring duration was significantly higher in obese users.
BMI and Sleep Quality
Sleep apnea reduces overall sleep quality, resulting in many of the daytime symptoms that affect a person’s ability to function, such as excessive sleepiness and cognitive issues. To determine if BMI plays a role in sleep quality, four different sleep quality indicators were assessed.
Sleep Efficiency
The first sleep quality indicator evaluated was sleep efficiency, which is a measure of the percentage of time a person is actually asleep vs. the amount of time they tried to sleep. Thus, a lower sleep efficiency percentage indicates that the individual spent less time asleep while in bed.
Both male and female users in the overweight category had a slightly lower average sleep efficiency compared to normal users. Obese users had a significantly lower sleep efficiency score than both normal and overweight users, demonstrating that obese users spend less time asleep while in bed.
Total Sleep Time
Next, average total sleep time was determined. Adults require 7-9 hours of sleep to maintain health. Both male and female users with an overweight or obese BMI slept for a shorter duration than users with a normal BMI. Obese women slept 36 minutes fewer on average and obese men slept 57 minutes fewer on average, demonstrating that having an overweight or obese BMI reduces your total sleep time and may cause chronic sleep deprivation.
Deep Sleep and REM Sleep
Finally, the percentage of deep sleep and REM sleep were calculated. Humans have 4 distinct sleep stages, 3 Non-REM stages, including stage 1 light sleep, stage 2 medium sleep, and stage 3 deep sleep, and the Rapid Eye Movement (REM) stage. Deep sleep and REM sleep are essential for restoring the brain and body and making us feel refreshed in the morning. The average percentage of deep sleep and REM sleep were calculated in normal, overweight, and obese users.
Interestingly, BMI showed little to no effect on the total percentage of deep sleep achieved, however REM sleep was significantly reduced in obese users, which suggests that BMI negatively impacts the amount of REM sleep an individual achieves.
The Takeaway
Wesper user data confirmed that body weight plays a significant role in a person’s risk for sleep apnea. Overweight and obese individuals are at a much higher risk for developing the sleep disorder than a person with a normal weight. The analysis also identified that being only slightly overweight carries the same risk for sleep apnea as individuals with a higher BMI.
Additionally, obese individuals are at the same risk for sleep apnea as those who are morbidly obese. Thus, morbidly obese individuals may have to lose significantly more weight before improving their sleep apnea. Finally, BMI appears to play a role in sleep quality, with obese individuals having worse sleep quality overall, compared to normal and overweight individuals.
While not all sleep apnea patients are overweight, this study demonstrates that weight plays a significant role in a person’s risk for sleep apnea and poor sleep quality. Weight management should be considered as part of a person’s sleep apnea treatment journey.
References:
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3021364/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2645252/
