Extreme sleep loss causes an immune response in the body similar to stress, a new study reports. Researchers in the Netherlands and United Kingdom compared white blood cell counts of 15 healthy young men under normal and severely sleep-deprived circumstances. White blood cell numbers showed differences in numbers and patterns after the men were kept awake for 29 hours straight.

Researchers said more study is needed to determine whether this immune response contributes to the development of diseases associated with sleep loss. Sleep restriction has been linked with obesity, diabetes and hypertension. Other studies have shown that sleep helps sustain the functioning of the immune system. Chronic sleep loss also is a risk factor for immune system impairment. The American Academy of Sleep Medicine recommends seven to nine hours of sleep for adults.

The study was published in the July issue of the journal SLEEP.