Naptime for Your Brain

“I drifted into a summer nap under the hot shade of July, serenaded by a cicada lullaby, to drowsy-warm dreams of distant thunder.” ~ Terri Guillemets

Having grown up in a few hot places, I can recall the absolute pleasure of a mid-day summer nap. As kids, we often napped outdoors by simply falling down in a favorite shady spot whenever the need for sleep overtook us. I remember waking up full of dreamy ideas, ready to jump up and go. I stopped being able to nap well before my teens, but people all around the world nap throughout life. I wondered if there is something to all that napping!

A nap is a short period of sleep typically taken during the day. Sleep researchers classify naps based on why they are taken: 

Nap Type	Definition
Recovery	Due to sleep loss
Prophylactic	In preparation for sleep loss
Appetitive	For enjoyment
Fulfillment	Due to increased sleep need (during development)
Essential	Due to sickness or inflammation (body or brain)

Overall, napping is thought to be beneficial to the brain. Perhaps best studied is the role of naps in learning and solidifying memory. This involves intricate exchanges between the hippocampus (essential in learning of new information), and the cerebral cortex (where long term memory storage and integration of of new and previous knowledge occurs).

 Naps, like nighttime sleep, can have several distinct stages. These include rapid eye-movement (REM) sleep and non-rapid eye movement (NREM) sleep which includes deep or slow-wave sleep (SWS). In the setting of overall adequate sleep, a nap may include mostly REM – as in infants, a combination of REM and early NREM in late childhood and young adults, or mostly NREM and SWS sleep in older adults.  Different sleep stages appear to play different roles in relation to learning and memory. REM sleep selectively either strengthens or deletes new neuronal connections and synapses; NREM and particularly SWS are important for transferring memories from temporary storage in the hippocampus to long term storage in the cortex.

Brain development research attributes frequent napping in infants and children to their need to learn and remember enormous amounts of new information pouring into the developing hippocampus. It is thought that children stop needing to take naps once their brain has become more efficient at downloading and consolidating what they are learning. Naps in children also support executive functions like working memory, may improve memory of motor skills, and improve emotional regulation – picture the epic tantrums when a toddler misses their nap. Several studies show that these benefits of naps are not just for the young, but can be demonstrated across ages.

Then, perhaps we should all be napping for the benefit of the brain? Well, there has been some concern regarding possible negative cognitive effects of frequent (essential) napping in older adults. However, studies show that the increased napping seems to be a result, rather than cause, of cognitive decline. It is thought that age-related degradation of neuronal networks and neurotransmitters, coupled with inflammation, disrupts proper sleep/wake balance and leads to excessive daytime napping in older adults with cognitive impairments. Most normally aging adults can safely enjoy a nap.

OK, if we are to nap, when and how long is best?  Research indicates that the Spanish got it right with their siesta habit. The optimal timing for a nap appears to be between 1 and 3 pm, when the circadian rhythms that regulate our sleep/wake cycle make us most drowsy. As for duration, short naps (20 minutes or less) increase alertness and cognitive performance, and are less likely to cause ‘sleep inertia’ – that fuzzy-headed feeling upon waking. Naps of 30 minutes or more tend to include SWS and produce sleep inertia, but may provide greater benefits for memory. Careful though, as longer naps can interfere with nighttime sleep.

So go ahead, savor the summer languor with a well-timed nap. But if, like me, you are not a napper, happily there seem to be no documented ill-effects of skipping naps altogether! 

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Post by: Nadia Fike

Read More: 1. Mantua, J and Spencer, RMC. Exploring the nap paradox: are mid-day sleep bouts a friend or foe? Sleep Medicine, volume 37, Sept 2017, pp 88- https://doi.org/10.1016/j.sleep.2017.01.019  2. Spencer RMC and Riggins T. Contributions of memory and brain development to the bioregulation of naps and nap transitions in early childhood.  Proc Natl Acad Sci USA, 22Nov; 119(44). doi: 10.1073/pnas.2123415119.