In a world where sleep deprivation is the new normal, there are medical students.
Most of us spend a third of our lives in this state of suspended consciousness and yet we still understand very little about what sleep really is. This ambiguity has led many to conclude that sleep may be wasted time. Society values output, efficiency and, by implication, sleeplessness. But what are we really sacrificing before the mighty altar of productivity?
Sleep has been linked to better mental health, cognitive function, and general wellbeing, and its absence has been correlated with a number of pathologies, including depression and hypertension. [1] It follows then that by cutting sleep in our quest for more time, we could end up sicker, sadder and stupider.
There is considerable evidence emerging in the form of both animal and human studies for the role of sleep in consolidating memory and learning, particularly procedural learning. [2,3,4,5,6] It is thought that learning tags neural pathways, which can then be reactivated and consolidated during the following period of sleep. [7]
But what about those times when we simply can’t make a full night of sleep?
In fact, sleep may not need to follow the traditional eight-hour block pattern to exert its benefit. A recent study showed that the natural deterioration in performance during repeated practice of a repetitive technical task was reversed by a thirty-minute daytime nap. [8] In the same study, subjects who napped for an additional thirty minutes actually experienced improved performance compared to their original ability, demonstrating the learning effect of sleep. The researchers went on to show that naps of sixty to ninety minutes can yield performance improvements equivalent to a normal night of sleep. [9]
The idea that a single afternoon nap can refresh the mind and enhance learning is particularly enticing to medical students and doctors, to whom the concept of an eight-hour sleep is often little more than a childhood memory. Such findings suggest that a biphasic sleep pattern (one sleep, one nap) may improve overall brain function, particularly if you need to maintain concentration and memory retention later into the evening. This siesta model is widely practiced in tropical climates to remedy the natural afternoon spike in sleepiness, and the phenomenon of power-napping has already entrenched itself in the vocabulary of the working public.
Of course, there are always those who insist on taking things further, which brings me to the vastly less scientifically validated portion of this article. Polyphasic sleep is a relatively new arrival on the scene, although its adherents cite the supposed sleeping habits of historical figures like Thomas Edison and Leonardo Da Vinci as early pioneers. It operates on the principle that much of our conventional eight hour sleeps are spent fluctuating through transitional states of semi-consciousness and low-grade rest and are thus wasted.
Building on the siesta model, by introducing more and more naps, the core sleep can be progressively whittled away, eventually culminating in the ultimate expression of polyphasic sleep, the aptly titled Uberman Cycle: a twenty-minute nap every four hours, indefinitely. That’s a total of two hours sleep per day!
While there are adherents posting on the internet who claim to have maintained rigid sleep diets like this for months and years at a time (i.e. Steve Pavlina), there is a notable absence of validated evidence for such minimalist sleeping patterns or their effects on wider health and cognition. Given the growing body of research asserting the importance of sleep for learning, performance and general wellbeing, I can’t in good conscience recommend such extreme sleep diets, no matter how appealing the idea of a twenty-two hour waking day might be.
What does all this come down to, aside from a thinly veiled excuse to live a Mediterranean siesta lifestyle? Firstly: sleep matters, and we medics are particularly prone to missing out on it. If you find yourself in a period of your life where adequate sleep is impossible (read “internship”), don’t underestimate the potential benefits of naps. Secondly: it could well be that sleeping is the easiest way to study that science has discovered so far. So next time you see me face down and snoring on my Talley & O’Connor’s, please don’t wake me or shake your head in disappointment–I‘m studying.
What are your sleeping patterns like?
References:
1. Skalski, M. (2010) Sleep Medicine. Overview of Medicine [Przeglad Lekarski], 67(9):721-5.
2. Ellenbogen, J.M., Hu, P.T., Payne, J.D., Titone, D. & Walker, M.P. (2007) Human relational memory requires time and sleep. Proceedings of the National Academy of Sciences, 104(18), 7723-7728.
3. Fischer, S., Hallschmid, M., Elsner, A.L., & Born, J. (2002) Sleep forms memory for finger skills. Proceedings of the National Academy of Sciences, 99(18) 11987-11991.
4. Rasch, B., Born, J. (2013) About Sleep’s Role in Memory. Physiological Review, 93(2), 681-766.
5. Wagner, U., Gais, S., Haider, H., Verleger, R., & Born, J. (2003) Sleep inspires insight. Nature, 427(6972), 352-355.
6. Walker, M.P., Brakefield, T., Morgan, A., Hobson, J.A., Stickgold, R. (2002) Practice with Sleep Makes Perfect: Sleep-Dependent Motor Skill Learning. Neuron. 35(1), 205-211.
7. Walker, M. P., & Stickgold, R. (2006). Sleep, memory, and plasticity. Annu. Rev. Psychol., 57, 139-166.
8. Mednick, S.C., Nakayama, K., Cantero, J.L., Atienza, M., Levin, A.A., Pathak, N., & Stickgold, R. (2002) The restorative effect of naps on perceptual deterioration. Nature Neuroscience, 5, 677-681.
9. Mednick, S., Nakayama, K., & Stickgold, R. (2003) Sleep-dependent learning: a nap is as good as a night. Nature Neuroscience, 6, 697-698.
10. Nishida, M. & Walker, M.P. (2007) Daytime Naps, Motor Memory Consolidation and Regionally Specific Sleep Spindles. PLoS ONE 2(4) 341.