For some of us, heavy eyelids are no strangers by the time the afternoon rolls around. But should we really be dozing off when the sun is out? Does it have a beneficial effect on our health in the long run?

The answer is far from a simple yes or no. There are some cases where the tendency to nap during the day could be an indicator of poor health. According to sleep experts, if you spend a majority of the day feeling sleepy, it may be a symptom of an underlying issue such as stress or insomnia.

One way to know is to observe how long your naps last — 60 minutes or longer is a sign that something is wrong with your sleep or your health, said Michael Grandner, Ph.D., director of the Sleep and Health Research Program at the University of Arizona.

Of course, it makes sense if your nighttime sleep is poor and inadequate, you likely won't feel alert and energized during the day. But napping should not become an everyday habit to compensate for lost sleep.

In fact, it could make matters worse as some people may wake up from the nap feeling more groggy and tired than before. This is known as sleep inertia, a disorienting state where the body tries to say it is not done recharging and is not ready to fully wake up yet.

But there is another group of people who can actually benefit from daytime naps. Due to their genetics, these individuals fall into a category known as natural or habitual nappers, which is different from napping to make up for lost sleep.

"These people — and they probably account for about 40 percent of the population — tend to do really poorly if they don’t nap," said Dr. Sara Mednick, a psychologist at the University of California.

Not only do they feel less sleepy afterward but also experience a boost in their mood, cognitive functioning, reaction time, short-term memory and more. As stated by the National Sleep Foundation, these are the benefits of what we call a power nap.

The term refers to a short nap of 20 to 30 minutes which can boost mood as well as productivity levels. Experts also note that 2 to 3 p.m. is probably your best slot for taking a nap as you naturally feel a bit sleepy right after lunch. 

Most importantly, remember to keep the naps short. Long and frequent daytime naps can leave you feeling sleepless at night, which can create a rather frustrating cycle for your internal body clock. And if you find that your nighttime sleep needs some improvement, here are a few tips you can follow to prepare your surroundings.