11
Some previous studies have linked the restriction and deprivation of sleep with the development of diseases such as obesity, diabetes and hypertension; while others have shown that sleep helps to sustain the operation of the immune system, and that chronic sleep loss is a risk factor for their deterioration.
In the new research, the white blood cells of the 15 subjects were measured and analyzed after a strict schedule of eight hours of sleep each day, for a week. Then the participants were exposed to at least 15 minutes of light outdoors within the first 90 minutes of wakefulness, and banned the use of caffeine, alcohol, or drugs during the last three days. This study was designed to stabilize the circadian clocks, and reduce to a minimum the lack of sleep, before intensive laboratory study.
Subsequently, the count of white blood cells in a normal sleep-wake cycle was compared with data from the second part of the experiment, in which blood samples were collected for 29 hours of continuous vigil. As a result, concludes Ackerman, granulocytes reacted immediately to the physical stress of sleep loss.