Back in 1993, Karl Anders Ericsson and his colleagues published research entitled The Role of Deliberate Practice in the Acquisition of Expert Performance. The research sought to understand how practice differentiated the ability levels of violinists.
Its first and most unsurprising conclusion was that those who practiced the most over the long run tended to be the best violinists. This was later crudely interpreted and popularised as “the 10,000-Hour Rule” by Malcolm Gladwell.
As the researchers have argued, Gladwell’s take dampens the emphasis on the type of practice being carried out, but also ignores that the best violinists had a wide range of accumulated hours of practice. An arbitrary number of hours therefore misses the point.
But here’s the fun bit. Forgive me for a moment if I indulge in the same kind of crude analysis. Because on a similar basis, what has become famous as “the 10,000-Hour Rule” should perhaps also become famous as “the 24-Minute Rule”.
Why? Because the best violinists napped on average for 24 minutes every day. That’s a whole 16 minutes more per day than the lower-ability violinists.
Put another way, the best violinists were powered by deliberate practice and deliberate rest. The more deliberate and intense the practice, the more deliberate and intense the nap. And the more deliberate and intense the nap, the more they extracted from the deliberate practice.
Granted, I’m jumping to conclusions based on averages. Which is why I’d like to walk through some of the vast pool of research which supports the following conclusion: when it complements stretching physical and mental work, a short, strategic nap (perhaps of 24 minutes) can be a productivity weapon.
The Stages of Sleep
To understand the power of napping, we first need to understand the stages of the sleep cycle.
The average adult has a sleep cycle of about 90 minutes, which consists of four stages. Stages 1-3 are our non-rapid eye movement (NREM) phases of sleep and Stage 4 is where rapid eye movement (REM) sleep occurs.
NREM Stage 1: At the beginning of our sleep cycle, we experience very light sleep, drifting in and out, typically for around 5 to 10 minutes. This is where we experience hypnic jerks between wakefulness and sleep.
NREM Stage 2: As we move into Stage 2, we become more difficult to wake, our body temperature drops, and our heartrate slows. Our brains start to produce bursts of recurring neural activity known as sleep spindles. This stage typically lasts for around 20 minutes.
NREM Stage 3: In Stage 3, we enter what is known as deep sleep. Slow brain waves known as delta waves show up in neural activity and we become much more difficult to wake. This is the stage in which sleepwalking and talking are most likely to occur.
REM Stage 4: Rapid eye movement sleep is our dreaming stage. Our brain waves become much more active than in other stages of sleep – similar to when we are awake – and it is much easier for us to be awoken than when we are in deep sleep.
To confuse matters, we do not go directly from Stage 3 to Stage 4. We move to deep sleep (Stage 3) before returning to light sleep (Stage 2) and then ending in REM sleep (Stage 4) before returning to light sleep again to begin a new sleep cycle. The result is that around half our sleep ends up being in Stage 2.
The length of cycles, time in each stage, and how many overall cycles we need will vary by person. As an overall indication, most of us will end up getting between 4 and 6 sleep cycles each night.
Why 24 Minutes?
There are a couple of important caveats we should take from our sleep cycles.
The first is that if we nap for over 30 minutes, we will likely end up falling into Stage 3 deep sleep. When we wake up, that means we will probably feel groggier (known as sleep inertia) than we would from a 24-minute nap. Indeed, should we wake ourselves up in the middle of our deep sleep stage, we are likely to feel even worse.
Most of the science therefore suggests napping should be limited to light sleep (i.e. 30 minutes or less) or a full 90-minute sleep cycle. The middle ground is not likely to produce the same immediate benefits.
The second important caveat is that oversleeping in the day can compromise our sleep cycles at night. Clearly, if we take a 90-minute nap during the day, unless we are already sleep deprived, it’s unlikely that we will feel as sleepy when we head to bed that night. There is also the small question of finding the time for such a long nap!
I therefore pitch for the 24-minute rule. This gives enough time to experience some of the restorative benefits of napping, without waking up groggy or undermining your evening’s sleep.
And with that, let’s turn to those benefits.
The Scientific Benefits of Short Naps
When I refer to the idea of a short nap, I’m referring to strategic naps of 30 minutes or less. If we are able to get to sleep quickly, these naps should get us a little light Stage 2 sleep, without entering Stage 3 deep sleep.
This distinction matters because during light sleep our brains perform a number of important performance-enhancing functions. Remember those “sleep spindles” in the brain that I referred to earlier? These are associated with several important functions:
- Increased synaptic plasticity: Studies suggest light sleep increases our brains’ capacity to form new synaptic pathways, a mechanism associated with forming habits and learning new skills.
- Memory consolidation, learning and performance: Research shows that sleep spindles increase in number and duration following new learning and are strongly correlated with performance improvements on tests, such as word recall.
- Higher intelligence: One study even highlights an association between sleep spindle density and IQ.
In addition to improving the above cognitive functions, short midday naps have also been associated with reduced risk of heart disease, reduced stress hormones, and improved alertness and reaction times.
We Were Built to Nap
Compounding all these benefits of napping is the daily indication that we are built to nap. Every day, typically between 1pm and 3pm, our desire to sleep reaches its peak in our waking hours.
While the timings of circadian rhythms vary by person, we all tend to experience this slump during the early afternoon. This is the main reason why early afternoon naps are common throughout the Mediterranean and Hispanic American countries.
The question, then, is why aren’t we all doing it?
The obvious answer is that monophasic sleeping (i.e. taking one long chunk of sleep) fits our established routines and norms. This is despite over 85% of mammalian species being polyphasic sleepers.
But even in the face of growing evidence on the benefits of short naps, there is another important factor stopping us all from adopting the 24-Minute Rule: the stigma.
Breaking the Stigma
I remember having a clear idea about siestas. And that idea was that they are one of the defining characteristics of lazy people.
People who sleep during the day lack ambition and drive, I thought. You earn the right to nap when you’re elderly. Before then, why would you waste your time sleeping in the day?
That characterisation may be right in many cases – just as the characterisation of laziness may be right in many cases for those who don’t nap. The problem was that I’d fallen into the trap of ignoring the possibility that napping served another purpose.
I had allowed stigma to blind me from the possibility that napping could be a performance enhancer. Far from demonstrating a lack of ambition, it could facilitate bigger ambitions. Napping wasn’t necessarily the lazy thing to do; it could be the smart thing to do.
Some companies, like Google and NASA, are beginning to recognise that, dedicating office spaces to the purpose of napping. But there is a long way to go.
The idea I could tell my colleagues I was going for a 24-minute nap after lunch without some raised eyebrows is absurd. Changing this requires businesses to lead the charge, actively encouraging employees to block out their calendar and take time to reboot.
The Two Principles of the 24-Minute Rule
But while we wait for that evolution, why not take the risk and lead?
There are just two important principles to the 24-Minute Rule that I urge you to consider before you lay down:
#1: Earn Your Nap: The science shows us that the effects and value of short naps are much more potent when we’ve stretched ourselves mentally and physically. So earn your nap. Stretch yourself cognitively and then enjoy the neurological fruits of a short nap. Don’t do nothing and nap. The chances are that this will do more harm than good. Consider the 24-minute nap a strategic performance enhancer, designed to complement your deliberate practice or deep work.
#2: Take Your Nap: If you have earned it, take it. Use your early afternoon slump after lunch to take 24 minutes of light sleep. This will help to consolidate the work and ideas you’ve been working on in the morning. Of course, not everyone will experience the benefits – we are all different – but the science suggests we have a decent probability of improving our performance.
The Time Is Now
At the time of writing, many of us have been forced into a virtual working environment. This isn’t easy, but for those in this situation, there is probably no better time to experiment with the 24-Minute Rule than now.
Imagine it. No odd looks as you head off to a quiet space to sleep (at least not from your colleagues). No judgement.
Now is perhaps one of the best opportunities you will have to try the 24-minute rule for yourself.
Like the best violinists, now is the optimal time to recognise that deliberate practice is enhanced by a deliberate nap.