Daytime power naps ranging from 2 to 30 minutes outside regular sleep are not just a bandaid solution to fatigue. They are an evidence-based method to recover from sleep deprivation, improve learning and memory, and reduce fatigue due to work stress.
What really are power naps?
The average restful sleep is 4-6 cycles lasting 1 to 2 hours each, where a single cycle has 4 stages. The first 3 are called non-rapid-eye-movement (NREM) stages, and the 4th is the rapid-eye-movement (REM) stage. The first stage is the lightest sleep, and then we enter progressively deeper sleep in stages 2 and 3. In stage 4, we experience vivid dreams where the body is in sleep mode, but the brain shows activity similar to wakefulness (that’s why it’s called paradoxical sleep). Power naps are 2-30-minute sleep sessions that don’t go through a full sleep cycle and only contain stage 1 and stage 2 (NREM), which are relatively light sleep stages, so it’s easy to wake up from them. Since NREM sleep lasts typically for 45 minutes to 75 minutes, power naps are limited to under 45 minutes on average, otherwise, it’s regular sleep, just cut short.
Fun fact: Research shows it is possible to dream in all stages of sleep across non-rapid-eye-movement and rapid-eye-movement.
James B. Mass, an authority on sleep, coined the term “power nap” in 1988 as a small 20-minute nap we can take during the middle of a workday to enhance productivity, motivation, and brain function, and reduce fatigue and catch up on much-needed rest. Essentially, it is a restoration activity to return the body to homeostasis and feel energetic to carry on with work. Soon after, the power nap became a lifestyle tradition during breaks and work hours and at home for many people to improve their productivity. Those who nap stand by its effectiveness.
Stage 2 sleep and sleep spindles improve memory and performance
The shortest power naps people do are 2-3 minute-long restorations. While these are useful for restoring attention by resting your eyes, they aren’t the most effective for improving memory or performance. They mostly only improve overall freshness. However, slightly longer power naps (15-20 minutes) include complete stage 1 processes and a few minutes of stage 2 sleep. And the biggest benefit of daytime napping probably comes from having both stages in your power nap. Research shows that memory, focus, and mood improve most when it includes a little bit of stage 2 sleep after completing stage 1. Stage 2 sleep is also very important for motor memory (movement and procedures like dance, music, assembly, repairs, etc.). So power naps with stage 2 sleep that lasts 15 to 30 minutes improve physical performance. Longer naps of 60 to 90 minutes can improve motor performance even more because the additional stage 2 sleep leads to better memory consolidation.
Tip: If you are learning any physical movement like repairs, dance, music, sports, or gym exercises, where your memory for movements is very important, take a power nap after you learn to fast-track your skill improvement.
Power naps don’t necessarily increase baseline productivity or well-being. They reduce deterioration due to sleep deprivation, stress, and unhealthy work habits. The amount of napping you need might depend on how much work you are doing. One study that looked at US Marine Corps during continuous work (20+ hours at a stretch) suggests that a 3-hour nap is needed to restore the brain for proper functioning, which translates to better performance and motivation during work. For professions like police, health care, security, air-traffic monitoring, etc., where work hours can easily cross a day, longer naps than traditional power naps are needed to restore fully.
A nap after learning something can improve memory because one function of sleeping is to solidify learning (which happens through a process called sleep-dependent memory consolidation). Researchers propose NREM and REM sleep both improve memory, so regular sleep and a short power nap can both improve memory. But specifically, sleep improves memory through 2 separate processes: Reinforcement and Refinement. Reinforcement is when the strength of memory increases, and it’s easier for you to recall, which happens during NREM sleep. Refinement is when a memory becomes more precise, and you learn if that memory is the right for a context, which happens during REM sleep. So ideally, if you learn something new, a power nap that goes into stage 1, 2, or 3 sleep (NREM) can potentially improve your memory. You can then use power naps to improve memory for words, new software, coding algorithms, recipes, sports/physical movements, protocols, etc. And then, when you sleep again at night, your learning will get precise and easier to execute the next day, which you’ll see as knowing exactly what to do when with little effort.
Real-world scenario: If you learn 3 different types of movements for 3 different scenarios, like making 3 different types of coffee foam art, NREM sleep will improve your ability to recall all 3 different movements and REM sleep will improve your ability to correctly choose which movement is most appropriate for a particular kind of coffee foam art. So power naps will make it easier to redo the movements, and long sleep will make it easy to choose the best movement from the 3.
During NREM sleep, the brain shows “sleep spindles,” which are short 1-second bursts of high brain wave activity. Studies show that these sleep spindles are important in protecting memory from interference, and spindles help consolidate memory. This means a memory that you acquire is reinforced during sleep when these spindles occur in the first 3 stages of sleep. And if what you are learning is prone to confusion or other learning interferes with it, spindles can protect the memory and make it stable. For example, suppose you learn a new vocabulary set and find some words confusing and keep interchanging their meanings. In that case, spindles can help each word differentiate and become stable, thereby reducing potential confusion.
Power naps or daytime naps that enter stage 2 sleep can improve declarative memory. Declarative memory is your long-term memory for facts and experiences which you can consciously recall. Sleep spindles occur during stage 1 sleep and are known to improve memory, and the same processes also occur during stage 2, making a thorough power nap very effective for improving long-term memory for newly learned information.
Some types of learning, which are about observation and quick attention to details in the visual periphery, improve slowly over time. There is a performance gain over multiple days. One study shows that observing details with your peripheral vision, which is a very important skill while driving or playing sports, or working in a hazardous factory/workshop, deteriorates if you practice a few times on the same day. While the reason for this is unknown and speculative, power naps tend not to deteriorate peripheral observation. This means power naps can make you more alert.
A new review of many past findings suggests that we may have overestimated sleep benefits. Sleeping/Napping has as a specific effect on memory and insights based on the task. For example, some studies suggest napping is an excellent way to extract a summary of new learning (called gist-extraction). If you learn a list of 10 words under a theme without knowing what the theme is, like names of trees or objects found in a bohemian decor, the brain will summarize them and gain insight into the theme. The quality of insight into the names of trees or bohemian decor would improve when the list increases with more examples. If the examples are weak and limited, the brain will likely summarize incorrectly. Researchers say that the brain needs more examples if sleep has to improve the accuracy of insights. So ideally, you may not want to power nap if you are learning something superficially. But you may benefit from a nap if your learning was intensive.
Another finding is that sleep improves memory recall and stability by strengthening fresh, fragile learning (known as memory consolidation). But diverse findings suggest that power naps aren’t the “active ingredient.” Time is. However, since power naps also improve alertness and mood, the overall effect of napping is stronger than not napping and just idling around.
How long the benefits of napping last are unclear. One study cited in their review observed that napping improved memory, and the improvement lasted for a week. Another study found that the benefit vanished in a week. As the authors suggest, the benefit of napping is highly task-dependent, and the effect is weak but not insignificant. But, the issue is bigger. Sleep deprivation worsens memory and brain function significantly across the board. Work schedules, long study hours, high demand for preparation and homework, etc., regularly force people to sacrifice sleep. This is when naps help. Napping can restore or reduce the damage done by sacrificing sleep. In a big-picture sense, napping has more practical significance than just its effect on memory.
Sleep inertia is a groggy brain-foggy feeling people get for a few minutes to hours after abruptly waking up, where they see a sharp drop in focus and productivity. This typically happens when a person suddenly wakes up during slow-wave sleep which is typically deeper sleep (stage 4). Power naps don’t enter deep sleep, but with sleep deprivation, one can enter deep sleep. And power naps that last longer than 1 hour end up transforming into deep sleep, which raises the chances of sleep inertia. One mechanism for this grogginess is adenosine, a neurochemical that lowers neural activity and alertness, is actively binding to adenosine receptors because of the deep sleep. Pick-me-up drinks like coffee, which contain caffeine, can counter this adenosine action because caffeine blocks out adenosine from binding and instead caffeine molecules bind to the receptor and stop adenosine’s lethargy-inducing effects. Eventually, sleep inertia fades, and the body returns to normal functioning, typically within 30 minutes of waking up groggy.
We are well aware of our needs and how napping affects us individually, and that is worth trusting. According to research, if we classify people as nappers and non-nappers, where nappers nap at least once a week and non-nappers don’t nap, the benefits of napping on task performance appear only in those who like to nap, and not in those who don’t nap. So if you feel you need to nap, you should because it is more likely you will see some benefit to productivity.
Research suggests no; short daytime naps don’t hamper nighttime sleep, and a majority of adults (74%) in the study had napped at least once in the 7-day study period, and half of them had a short under-20-minute power nap with no effect on nighttime sleep.
One study looked at the effect of preferred napping postures for a 30-minute power nap and how it affected their energy levels. The most preferred napping positions are horizontally on the bed, side-faced on the bed, or with the back reclined. All 3 positions improved alertness and energy equally, but those who got to nap in their preferred positions felt better after napping than those who napped in unpreferred positions.
The power nap process in the brain
How can we just fall asleep for a power nap, and do we have to be tired to take one? Researchers have observed that people can voluntarily lie down and sleep even if they aren’t chronically sleep-deprived, but are tired or sleepy. They propose 3 sleep “drives” that allow this.
- Sleep drive, which makes us sleepy during regular bedtime.
- Wake drive, which keeps us awake.
- Psycho-sensory drive, which wavers throughout the day and compensates for the difference between the sleep drive and wakefulness drive.
When a person is tired or overworked or underslept, their wake drive is high, but their sleep drive is higher. So then, the psycho-sensory drive adds to the wake drive and helps them stay up longer. Similarly, if a person naps and is well rested, the psycho-sensory drive disappears and then reappears when there is an imbalance between the sleep and wake drive. The psycho-sensory drive is heavily influenced by sensations and stimulation, which is why an alarm can wake a person up – the psycho-sensory sleep drive overrides the sleep drive and activates wakefulness. When a person power naps, just calling a person by their name or hearing a message or alarm can wake them up – the psycho-sensory drive is monitoring the outside world.
The psycho-sensory drive is theorized as the source of “power” in power naps. When it picks up stimulation like a phone call or alarm sound, it signals the brain’s Ascending Arousal System after traveling through the central nervous system. The AAS is located at the back side of the brain, near the brain stem, and includes many regions that govern basic bodily arousal by releasing neurochemicals like acetylcholine, serotonin, dopamine, and nor-adrenaline. The neural signals that occur via them instantly arouse the body and make us feel alert, motivated, energetic, and well-rested. And we see this – after waking up from a power nap, it is very easy to get back to work.
Sleep researcher Peter. T. George describes power naps as a state of consciousness called “Napitation,” which roughly occurs when brain waves are in the 5 to 10 Hz range. Generally, higher-frequency brain waves (above 30 Hz) occur when we are awake and alert. Brain waves slow down as we reach sleep till they reach 0.2 to 2 Hz, which is deep sleep. Napitation, or the power nap, lies in the transition between wakefulness to sleep.
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