Human napping has been explored in various research studies, and the results seem to disprove the masses who argue that naps are a waste of time. A 2008 study performed by Mednick, Cai, Canady, and Drummond concluded that a nap in the middle of the day had more of a positive effect than caffeine on energy levels, as well as learning, motor skills, and verbal memory. Numerous other studies all back taking short naps during the day not as a way to slack off, but maintain alertness and productivity throughout the day.
So there is strong evidence that short -or power naps- have a positive effect on our productivity, memory, learning and cognitive function. However, what is the correct amount of time to spend “daydreaming” per day? In this article, I’ll explore this very topic from a biological point of view.
10-20 Minute Nap
10-20 minutes is the lightest amount of time for a nap, save for the three minute head-bob during meetings. The 10-20 minute nap will not get you into full sleep, called Non-Rapid Eye Movement (NREM), but can still have you waking up feeling refreshed and ready to tackle the world.
When we sleep, our body enters various stages of the sleeping cycle. The 10-20 minute nap allows you to enter the first stage of restfulness, which is called the NREM stage. Here, the body falls into a light sleep where you can be easily awoken and, all things considered, your body is still fairly alert. The normal duration of stage one sleep lasts approximately 7-10 minutes, though it can last slightly longer depending on the person.
If you are more of a 20 minute napper, your brain may begin to enter Stage 2 sleep. Here, your brain wave frequency increases, called sleep spindles, and then slows down as it prepares for more deeper sleep. Waking up in this stage, though, can still leave you feeling refreshed and energized because the body has yet to enter a more trance-like sleeping stage.
The 10-20 minutes nap is most effective for when you feel yourself beginning to nod off in the middle of a boring meeting that should have been an email, or waiting for your kids to come out of school, or even for dinner as your husband is playing chef in the kitchen. You’ll wake up refreshed and ready to tackle the rest of your day after this type of short nap.
30 Minute Nap
The 30 minute nap is probably the most interesting of power naps. Here, the body is about to enter Stage 3 sleep. Stage 3 sleep is when the brain waves, or sleep spindles, begin to noticeably slow down as the body prepares for deep Rapid Eye Movement (REM) sleep. Waking up during any point of this stage, before the body has a chance to move through an entire REM Cycle, will leave you somewhat groggy and irritable upon waking. In fact, it will take some time before you start to feel the benefits of your nap.
However, like any other nap, sleeping for 30 minutes does have its benefits. Of all the above studies mentioned, the majority of their test subjects slept for 25-35 minutes, on average, and still showed positive signs of memory improvement, cognitive functions, and productivity.
The only time a 30 minute nap may not be a great idea is when you need to be alert the moment you wake up. Instead, opt for a twenty minute or a sixty minute nap.
A 30 minute nap is most effective when you need even more of a memory and cognitive boost compared to the 10-20 minute nap, and don’t need to be immediately alert upon waking up.
60 Minute Nap
The 60 minute nap is just as hard to wake up from as the 30 minute nap, if not more so, but it is also far more beneficial than its lesser counterparts. During the 60 minute nap the brain enters into Stage 4 sleep, which is one of the more reparative stages of sleep. However, the body has yet to go through a full REM cycle, even though it is in its beginning stages, so waking up after a 60 minute nap will still leave you feeling groggy, irritable, and slightly hungover and with a terrible taste in your mouth.
However, Stage 4 sleep begins the processes of muscle repairment and memory restoration. According to Harvard Medical School, there are two primary types of memory: declarative memory and procedural memory. Declarative memory is the “what” we know and have learned — essentially, all of the facts surrounding new information. Procedural memory is the “how” or “why” of any information we have gathered throughout the waking day, and helps us to remember specific functions and actions. However, without proper sleep, our brain cannot process these types of memories — called “consolidation” of memory — and, therefore, we have trouble recalling it when we are awake.
Stage 4 sleep helps to preserve our declarative memory. So, when we enter into a 60 minute nap, we have a better chance of consolidating and processes these declarative memories. In addition, the 60 minute nap is also imperative for muscle restoration and growth, which is very important if keep up with a consistent fitness regimen.
Again, just make sure you do not have to deal with anyone important after your 60 minute nap. And make sure to use some mouthwash before speaking.
The 60 minute nap is most effective and should be utilized when you feel yourself nodding off throughout the day, or are having a hard time paying attention.
90+ Minute Nap
The 90 minute nap is perhaps the most beneficial nap for your productivity and overall work output, but it is also the most time consuming. Therefore, it is normally the least likely to be utilized during the working day. However, the 90 minute nap is the most beneficial because this is the only time that our bodies enter into a full REM Cycle sleep.
During stages 3 and 4 of our sleep cycle, the brain tends to slow down its activity so that it can prepare for slumber. However, during REM sleep our brain kicks back into hard drive as it begins to process our procedural memories. Without entering into proper REM sleep, our brains will never be able to keep up with the amount of information it needs to process, and memory retention suffers. This is why, if you only get six hours of sleep one night when you are used to getting seven or eight, you have a tough time remembering something that had happened yesterday or two days beforehand. And, consequently, why you are having such a tough time remembering things today.
Though each person is slightly different, someone will generally fall into a REM cycle after ninety minutes of rest. Each REM cycle can last up to an hour, and we normally have about five to six per night. During this last sleeping stage we also dream, which causes the eyes to move rapidly beneath our eyelids — hence, Rapid Eye Movement sleep — as well as for our heart rate and blood pressure to increase and our breathing to become more shallow.
If you are considerably tired throughout the day, or are having a rather difficult time remembering whatever your boss said in that meeting the day before, take a 90 minute nap — or longer, if you can spare the time. Entering into a REM sleeping stage is the most beneficial to our long term success because it helps us to restore our memory banks so that we can process new thoughts and ideas. REM sleep also helps to boost creativity, memory retention and learning, and doesn’t leave us feeling groggy and hungover when we wake up.
The 90 minute nap is most effective for those who are having trouble remembering new information or recollecting old information, as well as falling asleep during the middle of an otherwise normal day.
Start Napping without Guilt!
I used to think of napping as a waste of time. After educating myself on the health effects of power napping, these days, I make it a point to nap for around 30 minutes after lunch daily, and meditating for 8 minutes just before bed to further de-stress and quiet the mind. The result has been nothing short of amazing. The 30 minutes I trade in to nap has resulted in a much more alert and energetic self afterwards; I get a lot more work done as a result, instead of feeling sluggish and like a zombie towards the tail end of my day.