The many benefits of sleep include helping individuals with alertness as well as cognitive abilities such as memory and concentration. We have also previously reported that individuals with a genetic vulnerability for obesity may benefit from getting an adequate amount of sleep. Now a recently published study reports that lack of sleep can increase insulin resistance at a molecular level in healthy individuals.
The study, which was published in Annals of Internal Medicinetested seven young and healthy participants in two different conditions which were then compared. The first condition consisted of the participants getting 8.5h of sleep in bed for four consecutive nights. A month later, the same participants underwent the second condition but this time they had 4.5 hours of sleep for four consecutive nights. On the last night of each condition the researchers gave an intravenous glucose tolerance test to each participant. In addition to that, a biopsy was performed on abdominal fat cells that had been removed from each participant’s navel. These cells were then used to measure how fat cells respond to insulin. In order to make the comparison fair, the researcher ensured that each participant’s food intake was identical in both conditions.
The key findings suggested that the insulin response decreased on average 16 per cent after four consecutive nights of little sleep, whereas the fat cells sensitivity to insulin decreased by 30 per cent. What is most notable is that changes were found in all participants.
Insulin, which is a hormone that helps the body process sugars, is intimately tied to fat cells, which in turn appear to be directly related to metabolic disruption and weight gain. If an individual is unable to process sugars, then more insulin is produced which can lead to various complications.
The researchers have argued that this study supports the link between sleep and diabetes and that it is their hope that sleep becomes included in recommendations alongside diet and exercise.
Although we understand the need for sleep, and have previously recommended that getting an optimal amount of sleep is good for a person’s health, we feel that the researchers’ conclusion may be a bit premature and only applicable to healthy individuals. To our knowledge, these types of studies are still in early stages and this study in particular had a very limited and healthy sample. Moreover, there is no current theory for what underlying mechanism controls the insulin response during sleep. Thus making the findings more descriptive than explanatory. Nevertheless, in the future we would be interested to hear about studies that have considered whether it is possible to reverse this effect with more sleep and in what way (if any) this effect may differ in unhealthy individuals.