New study done at the University of Chicago demonstrates interesting, but expected results: Sleep deprivation causes decreased insulin sensitivity with 30 percent in healthy young individuals. These results were seen only after 4 days of 4.5 hours of sleep!
Insulin sensitivity is the opposite of insulin resistance. Insulin resistance means that on a whole-body level the cells (fat cells, muscle cells) are less sensitive to the hormone insulin, which results in less uptake of glucose and fatty acids by these cells, which results in higher blood glucose levels. This, in turn, causes the pancreas to work extra hard to compensate for the insensitivity of the body cells to insulin by producing extra insulin. Overtime, the body cells become even more resistant to this hormone. It is a vicious cycle.
Insulin resistance is a pre-condition, leading to Type 2 diabetes – a major contributor to the metabolic syndrome, which is a collection of conditions, characterizing the self-inflicted, lifestyle-related disease of contemporary man in the modern society.
Regardless of the short duration of the study (4 days), the results are significant. 30 percent increase in insulin resistance is a serious matter for such a short period of time. And, considering the fact that in the contemporary fast-paced society most of us rarely get 8.5 hours of sleep, it can be said that chronic sleep deprivation – even several days in length – may contribute to worsening ones overall health by securing one of the five conditions in the collection of afflictions, called the metabolic syndrome.
Another study from the same university two years prior demonstrated that sleep deprivation (5.5 vs 8.5 hours) caused a decrease in the amount of fat lost (in overweight subjects) by 55 percent and increased the amount of lean body mass lost by 60 percent. This suggests that, in addition to insulin resistance, sleep deprivation also causes unfavorable alteration of the body tissues composition – more body fat retained, more lean muscle lost. The result – further slowing down of the metabolism via lowering of the Basal Metabolic Rate. Again, a vicious cycle.