German scientists recently discovered that getting a
good night's sleep is vital for boosting the effectiveness of the immune system's T cells, responsible for attacking any foreign bodies entering the system. When the body is asleep these cells activate integrins -- a type of protein -- which enable the cells to attach themselves to targets such as a virus and defend the body from attack. So by getting at least 7-8 hours a night (ideal amounts vary per person) you'll be doing yourself a world of good.