Many of us would like to take a nap, sometimes we just fall asleep.  When we wake up, we either feel wonderful or absolutely miserable.  Scientists have figured out how to maximize your nap.

The Wall Street Journal breaks it down by time.

A 10-20 minute nap is a power nap best to boost your alertness and energy.  Because it is brief, you don't feel groggy when you awake.

A 30 minute nap will cause what experts call sleep inertia, which they describe as a "hangover-like groggy feeling" which could last for a half-hour.  After that time period, the nap's benefits become realized.

An hour long nap is best for your memory.  It includes a phase of sleep that helps you remember facts, faces, and names.  However, you get the same feeling from a 30-minute nap.

A 90-minute nap completes a full-cycle of sleep.  It helps "emotional and procedural memory" and creativity.  Another benefit: no "hangover" feeling.

Other fun sleep facts

The Wall Street Journal article also offers other tips to help maximize sleep.

A mid-day nap, also called a siesta, is beneficial between 1 and 4 p.m., but the best time depends on when you wake up or go to bed.

Where's the best place to catch some quick z's?  Really, anywhere (specifically anywhere safe).  A couch, chair, bench, really anywhere that is comfortable.  However, experts say sitting slightly upright will prevent a deep sleep.

Younger people need longer naps, older people need shorter naps to be satisfied.