They think they're okay because they can get by on 6.5 hours, when they really need 7.5, eight, or even more to feel ideally vigorous.

他们认为自己的状态还可以，因为他们可以睡六个半小时来过活，即使实际上，他们需要七个半小时、八个小时甚至更长的时间，才能达到精力充沛的状态。