To sleep, perchance to learn

When recently asked about what superpowers she may want to have, one of my colleagues at work said she wished we did not have to sleep so that we can just have more time to consciously experience everything.  

I can just imagine how permanently busy and frenzied our brain cells will be if that were so.

Neuroscience has already established that we have the capacity to grow new brain cells called neurons, even when we have brain injury or as we age. This debunks old beliefs that we are born and will die with a fixed number of brain cells.

But what about those cells themselves as we grow up and learn more and more things. Do they change as well?

And then, remember that as kids, we generally hated being ordered to sleep early or take naps because we just always wanted to do things and we looked at sleeping as a waste of time. But what is the neuroscience behind sleep and learning?

Students and professionals who do all-nighters on reviews or presentations running only on caffeine may be wasting their time.

Many studies have been done and have confirmed that sleep has a direct effect on learning. These studies mostly compared learning test scores of people after they were made to sleep a certain number of hours or none at all.

This means that if you sleep well, then you can learn well. But what really happens to the structures of the brain when we learn and sleep on it? And equally important to know is, what happens when we don’t?

Learning while sleeping

A recent study published in the journal Science has shown that when the brain learns something and then sleeps on it, it actually grows new branches or spines in parts called dendrites.

Dendrites are a part of our neurons (a neuron is a kind of brain cell) that are responsible for sending signals for consolidation, before they are actually transmitted to other neurons by another part of the neuron called the axon.

They did the experiment on mice which they trained to balance off a spinning rod. Within 6 hours, the mice showed that it grew new branches on its dendrites. Then they compared mice which were made to learn different tasks for hours on a spin rod such as balancing and moving forward and backwards.

After each task, they made one group of mice sleep for 7 hours and another group was deprived of sleep. Those who slept grew significantly more branches in their dendrites than those who did not sleep.

This study linked the growth of dendritic branches to sleep. The tasks were focused on learning motor skills.  The authors also observed that different kinds of tasks grew specific branches showing that there is a structural change in our brains that occurs depending on the tasks we are learning. 

I asked the senior author, Dr Wen-Biao Gan, professor of neuroscience and physiology and a part of the Skirball Institute of Biomolecular Medicine at NYU Langone Medical Center, if this would apply to other types of learning that do not only involve motor skills.

He replied that for learning how to navigate a maze, which I assumed involved other cognitive aspects, there were also different branches that grew from that, different from learning how to spin a rod.

But is this capacity to grow new branches in our neurons ageless?

Key is regularity

I asked Dr Gan if there would be a difference in terms of age between the capacity of brains to grow new branches when learning. He said that their previous study in 2009 showed that more branches grew out of younger mice (one month old) than the older ones (older than 4 months).

He also added that while they did not examine aged mice, he would guess that spine formation in the dendrites would even be more reduced in aged mice after learning. 

And how about those with disrupted body clocks or circadian rhythms?  Dr Gan said that indeed, the time of sleep affects learning such as when your body rhythm is erratic, then learning would be a problem.

However, he also qualified it by saying that if you always work at night and sleep during the day, then your brain adjusts.  The key, I guess, is “regularity” and “stability” of the schedule of tasks that you do so that it is not significantly disrupted, ruining your own capacity to learn and learn better.

Sleep is anything but a silent, passive, dull activity. It seems to be the yin that needs to happen for the yang of learning to take hold.  

If Shakespeare could meet Dr Gan and his colleagues and talk about their many studies involving sleep and learning, the old bard would probably nuance another role for  “sleep” as not to die but “perchance” to learn and take on the world, yet again, with a “better” brain. – Rappler.com

Maria Isabel Garcia is a science writer. She has written two books,Science Solitaire and Twenty One Grams of Spirit and Seven Ounces of Desire. Her column appears every Friday and you can reach her at sciencesolitaire@gmail.com.

Tired student girl image from Shutterstock