Is this the perfect nap length? What to know about the NASA nap — plus 7 other ways to master mid-day snooze.

NASA isn't just unlocking the mysteries of space travel; they're also figuring out the best way to sneak in a little snooze without waking up groggy and feeling like you've wasted half the day. According to past research done on long-haul cockpit crews, there is a sweet spot in terms of nap length: 26 minutes. Crew members who slept for that long mid-day reported improved physiological alertness and performance compared to those who skipped a nap entirely. Bottom line: Take this as your excuse to doze off after lunch — but set your timer!

The so-called NASA nap isn't the only thing to know when it comes to the science of sleep. When is the right time to squeeze in a nap? What's the best way to fall asleep when it's still bright out? Are naps even good for you? (For most people, yes, research shows.) Yahoo Life spoke to sleep experts about getting more out of your naps so you wake up refreshed and ready to go on with your day.

Don't nap too late in the day

There’s no such thing as a perfect nap window for everyone, but there are ways of trying to figure out roughly when the best time for a nap is in your day.

“To understand the best timing for naps, we have to be aware of a concept called ‘sleep drive,’ or ‘sleep pressure,’” Rise Science clinician Karin Voelker, a licensed clinical psychologist specializing in behavioral sleep medicine, tells Yahoo Life. Voelker says sleep drive is the “hunger” for sleep that the human body builds by being awake throughout the day.

“A short nap can be compared to an appetizer and a long nap can act like a full meal,” she explains. Because of this, you’ll want to avoid napping within the eight hours prior to your bedtime so it doesn’t negatively impact your sleep. If you intend to go to sleep by 11 p.m., for example, you won’t want to nap any later than 3 p.m.

That said, “we tend to feel most sleepy in the early afternoon, during our natural circadian dip, so taking a short ‘power nap’ at that time may not impact our upcoming night significantly,” says Voelker.

Sleep medicine physician Dr. Funke Afolabi-Brown agrees that it’s often a good idea to take advantage of that energy dip to squeeze in some sleep. “That’s generally anywhere between 1 to 3 p.m., but definitely not beyond 3 p.m. [if bedtime is at 11],” she tells Yahoo Life.

Keep naps short and sweet

NASA is on to something: Sleep experts say the answer to avoiding post-nap grogginess is keeping your nap relatively short — ideally, half an hour or less.

“The grogginess we experience when waking up is called sleep inertia. We are likely to experience it if we go into deep sleep during our nap,” says Voelker. “Naps should be no longer than 20 to 30 minutes to avoid this.”

That said, our experts all say that there are exceptions that allow for a longer nap, such as if you’re making up for recent sleep debt. “This strategic napping can be very helpful for shift workers, or when experiencing jet lag due to a time zone change,” says Voelker.

Set the scene for sleep

Once you’ve decided on a good time for a nap, you’ll want to settle your body into rest. Falling asleep midday when the sun is shining can admittedly be challenging but not impossible.

“Your nap environment should mirror your sleep environment and be cool, dark and quiet,” Dr. Chris Winter, a specialist in sleep medicine and neurology as well as a sleep health expert for Mattress Firm, tells Yahoo Life. This might mean going back to bed and closing the blinds, stretching out on a couch or finding another comfortable space with minimal distractions. If you’re having to nap in a chair, look for one that reclines. “Be horizontal if possible,” Winter says.

“I would recommend you have a mini routine,” adds Afolabi-Brown, who suggests winding down with a shortened version of your standard pre-bedtime prep, such as slipping on an eye mask. In addition to providing some much-needed darkness, studies show that wearing an eye mask to bed can be beneficial, as it's linked to improving memory and alertness when awake, decreasing fear and anxiety (thus improving sleep quality) and potentially even increasing REM sleep in some subjects when coupled with earplugs.

Finally, if you’re having trouble slowing down your brain, consider sleep meditation to try and ease the flow of thoughts.

Don’t force it

Just because you feel tired doesn't mean you'll actually be able to fall asleep — and that's OK. “Approaching a nap with a goal to rest is more helpful than putting yourself under a pressure to actually sleep,” says Winter. “If sleep happens, great. If it does not, resting is very beneficial too.”

Afolabi-Brown agrees. “If it's taking you 15 minutes to take a nap, then you probably either don't have a high enough sleep drive or you're just actually not sleepy, and maybe you should just save that sleep drive for nighttime sleep,” she says.

If you do try and force a nap, you may end up doing yourself a disservice by cutting into your ability to sleep later in the evening.

Be consistent

Some of us just need an occasional nap on days when we're feeling especially sluggish, relaxing on vacation or recovering from a bad night's sleep. But if you are a frequent napper, experts advise making a routine around it.

“It is helpful to our brains to have a schedule for napping rather than just grabbing sleep whenever you can. This tends to minimize the sleep inertia some people feel with napping,” says Winter. If possible, he recommends napping at the same time every day, with the nap ending roughly around the same time, whether you actually sleep the full amount or not. If you don't have time for a daily nap, aim for the same timeframe on the days when you are able to lie down.

Wake back up with a post-nap routine

Just as waking up in the mornings feels easier after getting immediate sunlight, showering, exercising or even listening to music, you may also consider these activities post-nap. This will help ensure that you can get back to your afternoon activities, whether that’s work, picking up the kids from school or getting ready for a big night out.

Experts recommend using an alarm, making the room bright again and then getting some movement in (stretching is fine) after a nap. Winter suggests that food and some social interaction can also help you wake up.

Make sure you’re also focusing on getting a good night’s sleep

Finally, Afolabi-Brown recognizes that a good power nap can be great, but she also wants people to understand that what’s most important is ensuring that the sleep you get at night is well optimized. This means waking up and going to bed at the same time, having a good sleep routine and having restful sleep (versus tossing and turning or waking up multiple times a night).

If you’re feeling excessively tired on a regular basis, and as if you need daily naps just to function, experts say this may indicate a more serious issue such as insomnia.

“Insomnia patients need to be careful about long naps as this can lead to more issues with difficulty sleeping in the future,” says Winter. “In other words, if you got into bed and had the opportunity to sleep, but did not, napping during the day might be prolonging [or] worsening your sleep issues.” In these cases, seeking help from a medical professional is best.

?? Sleep better

• Doing simple exercises like chair squats, calf raises and standing knee raises with straight leg hip extensions can add 30 minutes to your nighttime sleep, according to research. [Yahoo Life]

• Try this viral sleep hack developed by the military. [Today]

• Maybe you should have a nighttime routine like a baby. "Sleep like a baby" is a saying for a reason after all. [Yahoo Life]

• A cooling blanket may help you get better rest. [Yahoo Life]

• Is magnesium foot spray the new 'sleepy girl mocktail'? [Yahoo Life]

• A sleep divorce may help. Don't knock it until you try it! [Today]

• The 4-7-8 method, which promotes slow, deep breathing, can help put you in the present moment, increasing relaxation and bringing on sleep. [HuffPost]

• Catching up on sleep on weekends may lower heart disease risk by 20%, according to research. [Yahoo Life]

• Soft bedding, mattress topper, duvet insert, fluffy pillows and more! Assemble a comfy sleep setup inspired by a luxurious hotel bed. [Yahoo Life Shopping]