When you’re tired, a nap always seems like a great idea, but timing and duration are keys to hitting the sweet spot of a healthy nap. Aim for a 10 to 30 minute nap around 2 or 3 p.m. in the afternoon. Longer naps will make you feel groggy and naps at this time are less likely to interfere with night time sleep.

Here are other key health benefits to napping.

What is going on in the brain during a nap?

In a recent study, researchers used a near-infrared device, which identifies specific networks inside the brain and how they work together, to decipher how the left and right brain were working during a nap.. Fifteen participants wore the device while they napped. Data showed that in both left- and right-handed people the right brain is more active and communicative. Researchers speculate that during the nap, the right brain was busy storing and processing information, daydreaming or other creative tasks.

Another recent study looked the way infant rat whiskers twitch while they nap, and how that may actually shape the brain. The study of rat whiskers has become very popular among neuroscientists, because each whisker maps to discrete regions in the brain that process information from that individual whisker. Researchers found that the infant rat whiskers twitched involuntarily while napping in very complex ways, which were tied to bursts of activity in the brain--something that is not often observed when rats are awake. Researchers believe this twitching may be shaping specific neural circuits and developing the sensorimotor systems. Humans have similar spontaneous movements during sleep, such as rapid eye movement and limb movement, which could also play a role in early development.

Another study has found that when you are sleep deprived parts of the brain may take a quick nap while the rest of the brain appears awake, which can lead to momentary forgetfulness. Previously researchers believed that sleep deprivation affected the entire brain, but now, through electroencephalograms (EEGs), scientists have found that our brain experiences short periods of “micro-sleep,” and this study shows that prior to micro-sleep, the brain is already showing sleep-like activity in certain regions.

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How do naps affect children?

Not only do naps possibly help our brain develop, but they also help us grow, according to a 2011 study of babies and naps. Researchers found that peaks in total daily sleep duration and number of times an infant napped during the day was associated with growth spurts in body length. These bursts in growth tended to occur within 48 hours of the sleep peaks. After analyzing data from 23 infants, researchers found that the probability of a growth spurt was increased by 43 percent for each additional nap and 20 percent for each additional hour of sleep.