Article Review: Affect of sleep duration on BMI, and associated hormones
Article:Taheri, S., Lin, L., Austin, D., Young, T. and Mignot, E., 2004. Short sleep duration is associated with reduced leptin, elevated ghrelin, and increased body mass index. PLoS medicine, 1(3), p.e62.
Design: Longitudinal study of 1024 volunteers. Collection of data included; nocturnal
polysomnography, self reported sleep questionnaires, blood samples and serum hormone levels were analysed.
Findings: There was a U curvature relationship between sleep and BMI, with 7.7hrs being the duration associated with lowest BMI. They also noted a decrease of serum leptin and an increase in serum ghrelin with shorter sleep times. (15% difference decrease and increase respectively for each hormone associated with 5hrs sleep compared to 8hrs sleep).
Limitations: This is a longitudinal study and real-life conditions. This means data is self reported and not 100% accurate as well as being longitudinal it only provides correlation not causation.
My Thoughts: From this study there is a clear association with a reduction in sleep correlating to an increase in BMI. The study shows that there is also correlation in leptin and ghrelin levels, what this means that with a reduction in sleep leptin is decreased (The hormone that tells you you are full) and ghrelin is increased (The hormone telling you you are hungry). Putting this into context could show the reason for the increase in BMI, as people lacking sleep have a much bigger 'hunger' and therefore tend to over-consume food leading to weight gain. Interestingly enough the increase in BMI with more than 8hours sleep was an interesting find, this could have be due to the lack of time to complete adequate energy expenditure to even out the energy intake as there was no finding of changed hormone levels. What I would like to add is that this is a correlation not causation, although the science does make a lot of sense. Get some sleep ya'll!