Listening: Fill in the Blanks #151039

You've probably 1 you're more likely to catch a cold if you pull a lot of all-nighters. But lack of sleep can also compromise your immune system's 2 to vaccines. And in some cases, make the shots useless. So says a study in the journal Sleep. Researchers gave 125 healthy, middle-aged men and women the Hepatitis B vaccine—a three-part vaccine given at one, two and six months. And during that time, volunteers 3 their sleep habits. Six months after the final booster, researchers took blood samples to see if the patients had rallied sufficient numbers of antibodies against Hep-B. Eighteen patients had not—the 4 had failed. Turns out the vaccine was almost 12 times as likely to fail in volunteers who regularly slept fewer than six hours a night compared to those who snoozed more than seven. Makes sense, because 5 studies have shown that sleep deprivation cuts numbers of B and T cells— which 6 the immune system's attack on bad guys. So remember, vaccines aren't magic. You still need a good night's sleep to give 'em a fair shot.