Suzy Eats

In the beginning of the 20th century, young American adults were sleeping almost 9 hours each night. By the 1960s, though, this had decreased to less than 8 hours a night, and by the year 2005, 16% of adults were sleeping last than 6 hours per night.

Sleep and obesity are similar to the chicken and the egg. In many ways, it is difficult to know which came first. Obesity is a risk factor for a number of diseases that can negatively impact sleep, such as sleep apnea, asthma, depression, and arthritis…so it is hard to tell if it is the decreased sleep causing the obesity or the obesity causing the decreased sleep.

A study conducted in women reporting their sleep habits and body weight every two years for a >15 year period was conducted. This study suggested that women who sleep less are more likely to gain weight and become obese in their middle-age. The same study showed that women who slept at least 7 hours per night weighed about 5 pounds less than those who slept 5 hours or less per night. These patients were followed for more than 15 years and the same pattern continued.  Since the number of sleep hours is self-reported, there may be some inaccuracy as many time people over- or underestimate their sleep pattern.

A more objective study looking at sleep time and weight has also been conducted which assessed two men and women aged 65 and older. Wrist actigraphy, which measures wrist movement, was used instead of self-reporting to determine sleep patterns. The results demonstrated that both men and women had a higher body mass index or BMI if they had less sleep. Men who slept 5 hours or less were ~ 4 times more likely to be obese while women were about 2.5 times more likely to be obese. 

So the research shows that less sleep=more weight but WHY????

One theory is that less sleep causes increased or altered food intake; increased hunger with sleep deprivation may be another reason. Also, increased food intake may occur even in the absence of hunger due to reduced impusle control or trouble delaying gratification which are consequences of less sleep. Finally, the more you are awake the more time you have to snack and if you are tired because you have not slept enough you may also be more tired and not able to exercise. 

We definitely know that less sleep is associated with obesity…the exact reason we still do not know. As we have seen from history though, our current society is definitely sleeping less than in the past. It would be great if we could start encouraging more sleep 🙂 

How many hours do you sleep at night???