Zebras, antelope, and other species take advantage of the giraffes' security system and often line up to drink with them. Fortunately for giraffes, they can go weeks without drinking. But sleeping is another story. Giraffes have to sleep every night, and they are even more vulnerable to attack when lying down than when drinking. This is because standing back up is a lengthy three-step process that involves vigorously swinging their necks backwards and forwards, first to hoist their forelegs to kneeling, then to get on their hindlegs, and finally to get up on their forelegs as well.
Giraffes have two strategies to minimize their chances of being attacked while sleeping.
As when drinking, at least one member of the herd always stands guard while others sleep. Second, their idea of a good night's sleep wouldn't satisfy even the most manic of us. Giraffes sleep deeply for only five minutes at a time and these naps add up to only about half an hour each day. They do supplement their naps by dozing standing up, but remain alert during these periods, leaving one eye open, and constantly moving their eight-inch ears. Besides spending a lot of time watching for danger, giraffes spend a lot of time browsing.