Association between weight gain, obesity and sleep duration

I suppose we have all heard lot of the saying that sleep duration strongly affects our weight and health. And according to a study, both short and long sleep hours are indicators to predict an increased risk for future health (Science Daily, 2008), and there are a lot of controversies out there nowadays regarding this topic. Therefore, in order to explore it further, I will be gladly introducing the research study called association between weight gain, obesity and sleep duration on a large-scale 3-year cohort study, done by St. Luke’s International Hospital in Tokyo.   

So basically, Kobayashi D., Takahashi O., Deshpande G., Shimbo T.& Fukui T. (2011) performed this retrospective study that surveyed 21,469 healthy individuals who were 20 years or older who had annual health checkups at St. Luke’s between 2005 and 2008. And the purpose of attracting all these apparently healthy citizens was to promote early detection of any chronic diseases (Kobayashi D. et al, 2011). Also, questionnaire about their average of sleeping time per night were filled out. In addition, statistical measures were used in conducting the research. For instance, the responses were analyzed using descriptive statistics like mean and standard deviation. As well as regression analysis which was used to explore the relationship between sleep duration, age, gender, past medical history, and level of physical activity (Kobayashi D. et al, 2011).

The study had found that those who slept for 7 hours are less likely to come obese than those who slept for 5 hours or less. And to contrast, individuals who slept more than 8 hours had no huge difference comparing to the 7-hour-sleepers in terms of their body mass index, but have a tendency to become obese in the future (Kobayashi D. et al, 2011). The result was interesting because it was not like the longer we sleep, the less likely we will be obese, but instead, more than 8 hours of sleep will contribute to increasing chances of weight gain or new-onset obesity.

As for the conclusion, the findings of this research study suggest that the optimal sleep hour for a healthy weight is around 7 hours per day. Additionally, sleeping less than 5 hours results in both weight gain and increasing potential risk of obesity for both males and females (Kobayashi D. et al, 2011). However, this study may be biased in the sense that the data collected is only from people who are healthy and coming to annual check-ups with this specific hospital. Thus, this sample does not represent the overall population. Other limitations might be that the questionnaires used did not incorporate information on quality or satisfaction of sleep. Also, it is a retrospective research, which means that larger sample size and perspective method will be needed to support the results.

I guess after knowing this fact, I will stick with sleeping 7 hours every day. Will you?

References:
Kobayashi D., Takahashi O., Deshpande G., Shimbo T.& Fukui T.(2011). Association between weight gain, obesity and sleep duration: a large-scale 3-year cohort study. Sleep and Breathing. 1-5 

Science Daily, 2008. Short, Long Sleep Duration Is Associated With Future Weight Gain In Adults. Retrieved from http://www.sciencedaily.com/releases/2008/04/080401081932.htm