Find out how long you should be napping each day. Jan 26, Waking from this stage results in sleep inertia, that grogginess and disorientation that can last for half an hour or more. But you might want to take a long nap, at least 90 minutes. Mar 10, Randy Gardner currently holds the official scientific record for longest sleep deprivation. In , he kept awake for consecutive hours (11 days) without the use of any stimulants. Gardner achieved this record when he was only 17 years old.