With their eyes closed, of course! Kidding aside, giraffes have some of the most unconventional ways of sleeping. Because they are the tallest living land animals courtesy of their necks that could reach to 6 feet long, it requires them a lot of effort and balance to stand up from the sitting position.
Thus, these gentle giants would rather rest standing on their legs than risk being the lions' dinner. In this position, giraffes can immediately run to safety in case they sense an attack from predators. They can run up to 35 mph, which gives adult giraffes a fighting chance to escape hungry predators which see them as moving buffet spreads! Unfortunately, it is not the same case for younger giraffes especially the newborns. About half of young giraffes fall prey to lions during the first year.
Sometimes, giraffes also sleep recumbent (lying down) and When they do, they usually rest their necks on their rumps or rest their heads on their hindquarters or ground and holding the neck in an arced posture. They also use some other prop like a log or rock, sort of a pillow that supports and keep their heads elevated.
According to studies, the giraffe has one of the shortest sleep requirements of any mammal. An adult giraffe sleeps between ten minutes and two hours in a 24-hour period, averaging about 2 hours per day. It may catnap lightly now and again during the day, but its ears are still highly sensitive and can sense movements of predators. This is how these creatures evolved to adjust and defend themselves from the dangers that lurks in the bushes.