Severe sleep loss jolts the immune system into action, reflecting the same type of immediate response shown during exposure to stress, a new study reports. Researchers in the Netherlands and United Kingdom compared the white blood cell counts of 15 healthy young men under normal and severely sleep-deprived conditions. The greatest changes were seen in the white blood cells known as granulocytes, which showed a loss of day-night rhythmicity, along with increased numbers, particularly at night.
