Sleep deprivation and physical stress have similar effects on the immune system of human beings, researchers from the Netherlands and the United Kingdom reported in the journal SLEEP. Both physical stress and severe sleep loss jolt the immune system into action, the authors explained.

The scientists , from Erasmus MC University Medical Center Rotterdam, and the Faculty of Health and Medical Sciences at the University of Surrey, United Kingdom, compared the number of white blood cells in 15 healthy young adult males who were subjected to normal sleep and severe sleep loss.

The greatest impact was on granulocytes – types of white blood cells – which lost their day-to-night time rhythmicity as numbers shot up, especially during nighttime.

Lead author, Katrin Ackermann, PhD, said:

“Future research will reveal the molecular mechanisms behind this immediate stress response and elucidate its role in the development of diseases associated with chronic sleep loss. If confirmed with more data, this will have implications for clinical practice and for professions associated with long-term sleep loss, such as rotating shift work.”

The authors explained that prior studies had found a link between lack of sleep and the development of certain diseases and conditions, such as high blood pressure (hypertension), diabetes and obesity. Other studies have demonstration that adequate sleep helps keep the immune system working properly, and that long-term sleep loss is a major risk factor for immune system problems.

The 15 young men were made to follow a strict routine of eight hours sleep every day for one whole week – their white blood cells were categorized and measured. Within 90 minutes of waking up, they were exposed to 15+ minutes of outdoor light. They were not allowed to consume anything with caffeine in it, they were told not to drink alcohol or take any medications. The aim here was to stabilize their circadian clocks and bring sleep deprivation down to a minimum before the intensive laboratory study.

The scientist compared the participants’ white cell counts during their normal sleep/wake cycle week to the count during the second part of the experiment when the subjects were made to spend 29 hours without any sleep at all.

Ackermann said: