Sleep is one of the main components of AARP Staying Sharp, a new initiative that aims to help seniors keep their brains healthy.

As you go about your daily activities, your brain is exposed to thousands of stimuli — auditory, visual, neurosensory. And it can’t possibly process all that information as it comes in. A lot of the tagging and archiving of memories occurs at night while you’re sleeping. It’s a bit like what goes on in a library. All the books dropped off in the book repository during the day are dusted off and cataloged at night. People who think they’ve adapted well to sleeping just four or five hours a night are often wrong; memory tests show they are not functioning optimally.