Though the exact relationship between sleep and growth isn’t clear, researchers believe it could be due to the release of growth hormone during sleep.

Toddlers are another group of children who benefit from naptime, according to a study from the University of Colorado Boulder. Researchers found that toddlers between 2.5 and 3 years old who missed one daily nap showed more anxiety, less joy and interest and had more difficulty solving problems. In addition, less sleep altered the facial expressions of toddlers, with exciting events being met with a less positive attitude, and frustrating events met with a more negative attitude. Eventually, researchers say this sleep deficit may shape their brain and put them at risk for lifelong, mood-related issues.

               [SLIDESHOW: 8 Interesting Facts About Dreams]

Do naps help seniors too?

While older people may try to stave off a nap in the afternoon so as not to appear lazy, napping can actually give them more energy to participate in social activities, according to a 2010 study. People tend to have more sleep problems as they age, whether it’s getting up in the middle of the night to urinate, or just waking up several times during the night. This can leave them exhausted during the day. Taking an afternoon nap can actually improve quality of life and energy during the day, according to researchers.

Can naps help us learn?

One study published in 2010 found evidence to suggest that people who take a nap and dream about a task they’ve just learned will perform the task better upon waking, than either those who don’t sleep at all or who sleep but don’t report an associated dream. Participants in the study were asked to sit in front of a computer screen and learn the layout of a 3-D maze to find a landmark. The participants were then put down in a random part of the maze five hours later. Those who napped and dreamed of the task found the landmark in less time. Researchers say that the dreams are likely a side effect of unconscious parts of the brain working hard to remember the virtual maze, rather than the dreams leading to better memory.

Another 2010 study found that napping can even boost brain power by clearing out temporary storage space. This can leave the brain open and ready to absorb new information. This study found that an hour nap can refresh the mind and make you smarter. The researchers likened the hippocampus to an email inbox, saying that when it gets full, you need sleep to initiate the clearing process. If you don’t sleep, the incoming information will just bounce into another “folder.” This process was seen to take place in stage 2 sleep. Now researchers are curious as to whether the deterioration of sleep in older people is associated  with the reduction in learning capacity as we age, and particularly Alzheimer’s disease.