Most medical authorities agree that adults need a minimum of seven hours of sleep per night
to be healthy, and teenagers need up to ten hours! Research shows that sleeping is an
important time for immune system activity, cell regeneration, healing, and renewing energy
stores. Most of us consider sleep to be important, but still, we do things that interfere with making
a good night’s sleep a priority. The CDC (Centers for Disease Control) estimates that 30 – 40% of
Americans sleep less than seven hours per night on a regular basis. They also found that people
who don’t get adequate sleep are more likely to be obese, physically inactive, and smokers. The
reasons for poor sleep generally have to do with modern lifestyle factors- too many electronics,
too much stress, and extremely hectic schedules.

A study from the UK was recently published on the topic of how sleep impacts overall health.
The researchers were interested in identifying the reasons why poor sleep leads to weight gain.
Does fatigue cause people to increase their calorie intake, make poor food choices, or are there
other medical reasons? To look for answers, they accessed data from a large nation-wide study called the
National Diet and Nutrition Survey.

They did confirm that the people who slept longer had a lower BMI (body mass index- a system
used to calculate obesity) and a smaller waist circumference than people who slept for shorter
times. Surprisingly, they did not find a strong correlation between food choices and sleep
duration as the researchers had originally presumed was the cause. They found that people
who slept less did not consume significantly more calories or have different diets as compared
to people who slept over seven hours. So the question remains- what causes the weight gain related to lack of sleep?

There are no clear answers, but there are a few theories. Researchers suggested as one
possibility that shorter sleeping times may cause slowing of the metabolic rate – the rate at which we burn calories at rest- leading to weight gain. If we think of sleep as a “tune-up” for the body (replacing worn out molecules and cells) then, with less sleep, maybe our bodies are more “worn out” and sluggish. It’s also possible that people with a higher BMI inadvertently underreported their food intake.

There was also a slight, but not a significant correlation between thyroid levels and sleep; people
who got less than seven hours had slightly lower thyroid levels. We know that low thyroid
hormone, as in the case of hypothyroidism, can predispose a person to weight gain, but it’s
unclear if that is the underlying problem related to lack of sleep.

We may not fully understand why poor sleep causes weight gain or why it causes thyroid levels
to decline, but we do know that getting a minimum of seven hours sleep per night is important
for our health. Read more about the relationship between thyroid and sleep patterns HERE.

References:
Potter GDM, Cade JE, Hardie LJ (2017) Longer sleep is associated with lower BMI and favorable metabolic profiles in UK adults: Findings from the National Diet and Nutrition Survey. PLoS ONE 12(7): e0182195. https://doi.org/10.1371/ journal.pone.0182195

CDC website: https://www.cdc.gov/sleep/data_statistics.html