Science and Technology

Long Read: The Science of the Sleeping Brain

Article by Amy Barrett August 7, 2018

What happens to our minds and bodies during our non-waking hours? Editor Amy meets cognitive neuroscientist Dr Matt Jones to talk about the importance of getting a good night’s sleep.

On average we will spend one third of our lives asleep. We can survive for longer without food than sleep yet we often neglect our bedtime routines. It becomes habit to sacrifice a good night’s sleep for a party, to work late or for an all-night study session. Dr Matt Jones, a cognitive neuroscientist at the University of Bristol (pictured right), is currently looking into the effects of sleep on our brains.

“My particular focus is on the role of brain activity during sleep in supporting learning and memory. But there’s much more to sleep than that.” A good night’s sleep will help us to study and work more efficiently, and we’re all in a better mood if we have woken up feeling refreshed. Though we might not be able to describe the how or why, we know that during sleep our bodies repair cells and tissues. A good night’s sleep encourages a stronger immune system while a bad night’s sleep can even contribute to weight gain.

And the effects of sleep deprivation aren’t just internal: tiredness causes more deaths on the road than alcohol or drugs. People who sleep for 6–7 hours a night are twice as likely to be involved in a car accident than their alert counterparts getting the full eight hours’ sleep (according to the AAA Foundation for Traffic Safety). Drivers will always take to the wheel drowsy, with 37% of people saying they have fallen asleep while driving.

The sleeping brain

Dr Jones briefly describes what changes occur in the brain when we sleep: “It’s kind of surprising that sleep isn’t like turning the volume down on the brain, but actually many parts of the brain are more active during sleep than they are during waking hours. Broadly speaking, sleeps roles can be subdivided into metabolic and restorative versus information processing or cognition. What happens to the brain during sleep very much depends on which part of the brain you are looking at, and which stage the brain is at in sleep.”

Sleep is subdivided into Rapid Eye Movement (REM) and non-REM stages, and the pattern of brain activity during those stages is very different. During REM sleep our brain activity looks similar to that of someone who is awake. Whereas in non-REM sleep our brain is expertly working, with stage 2 of non-REM showing peaks of high-frequency brain activity, correlating to the process of memory consolidation. Stage 3 appears as low waves with our heart rate and blood pressure dropping into a truly deep sleep.

There are lots of drugs that make you sleep more, but they don’t always improve the quality of sleep in terms of what’s going on in the brain

 

Some people believe sleep is essential to ‘gist’ learning – drawing general conclusions about what’s going on in your world based on individual experiences. “Obviously we don’t actively encode new information during sleep,” comments Dr Jones, “but we do actively process information that has been recently acquired into memory. Sleep offers an opportunity for the brain to do its filing – sort the wheat from the chaff, latch onto important stuff, integrate different memories that have been learned independently but have elements in common.”

How does the brain decide what’s important to keep and what isn’t? As for most things in the field of neurological science, there isn’t a categorical answer. But as Dr Jones explains, “there’s good evidence that, for example, information about rewarding experiences that you’ve enjoyed during wake will be reactivated during sleep and processed in memory consolidation. And it makes sense that salient, or important features of your life, like unexpectedly stumbling onto a pot of chocolate, are the kinds of things that you’ll then consolidate during sleep so that you can act on them in the future. On the negative side, aversive experiences and traumatic memories are also processed during sleep.”

Psychiatry and sleep

Dr Jones’s research has focused on the connection between sleep and psychiatric disorders, primarily schizophrenia. Since it was first described clinically it has been acknowledged that schizophrenia patients suffer from sleep problems.

“But the nature of those problems has remained enigmatic. It’s also more complicated because many of the drugs that people are given to treat schizophrenia (anti-psychotic drugs, for example) also have an impact on sleep, so it’s hard to disentangle what is causal (what is part of the disease) and what’s downstream of the disease.”

In a recent study with a lab at Harvard Medical School, Dr Jones’s team recorded sleep EEG (brain activity data that shows when people are awake or asleep, and subdivides activity into non-REM and REM stages) from a cohort of schizophrenia patients. They found that brain activity was disconnected in a way that meant memories were not being consolidated, and that different parts of the brain weren’t ‘tuning in’ to each other in the way they would for a healthy individual.

Imagine a scenario in the near future where healthy people could just wear a headband which could improve the quality of your sleep

 

This study was relatively small scale, and the patients taking part were on a range of medications, it was difficult to interpret the results definitively. Dr Jones hopes that by studying healthy individuals whose genes put them at risk of developing schizophrenia it can help us to understand the connection between schizophrenia and sleep.

“One study being run at the moment looks at these people, and we’re also starting to pick out abnormalities – only subtle ones but, given that we sleep every night, over the course of our entire lives, a subtle abnormality can have a large cumulative effect.”

These findings have led Dr Jones to consider ways that they can re-coordinate brain activity in those people who are at risk of developing schizophrenia. “Some drugs have the potential to help. Obviously there are lots of drugs that make you sleep more, but they don’t always improve the quality of sleep in terms of what’s going on in the brain. Actually, there are some drugs like benzodiazepines for example, which historically were used to help people sleep more, that disrupt brain activity and compromise some aspects of sleep’s function.”

Stimulating the brain during sleep

Dr Jones and his team are even working on ways to directly control the brain’s activity during sleep using stimulation. “There are quite a lot of people around the globe doing this kind of work. If you play auditory tones, just brief, quiet beeps during the night, without waking people up you can actually influence the timing of brain activity. And if you implement a feedback control system (using EEG to record brain activity) and at the right time relative to that brain activity you play a tone you can use that to kind of reset the system and synchronise things. So that’s what we’re working on at the moment – we and many other scientists around the globe.

“I imagine a scenario in the near future where healthy people, who may have sleep that from a neurophysiological perspective is not optimised, could just wear a headband that is recording brain activity; very comfortable, non-invasive, maybe have a little ear piece that’s feedback controlled from that headband, which could improve the quality of your sleep.”

Sleep habits

So has Dr Jones’s research influenced his own bedtime routines? He laughs. “I’m slightly embarrassed to say other than buying a much more expensive pillow, my research hasn’t had much of an impact on me, I lead a pretty dull life anyway! But it does make me think twice about optimising my approach to bedtime. We all know from experience that if you’re working late, staring at a computer screen, right before you go to bed then you tend not to sleep so well. I’d like to try to avoid that, but I’m not so good at it!”

He isn’t the only one: a poll by the National Sleep Foundation found that 51% of Brits are getting less sleep than they need on work days, and 27% of respondents said they can rarely or never say ‘I had a good night’s sleep’. While there are many illnesses and disorders that can affect sleep, the rise of technology has given us another reason to stay up later into the night. Paul Martin, author of Counting Sheep, explains that “Evolution equipped humans… with biological mechanisms to make us sleep at roughly the same time every day. However, those mechanisms evolved to cope with a preindustrial world that was vastly different from the one we now inhabit.”

Checking your phone at night results in poor quality sleep, research shows © KristopherK on Pixabay

The use of smartphones has been on the rise since Apple introduced the iPhone in 2007, with 81% of UK residents owning a smartphone. The younger generation are more susceptible to the calls of social media, with nearly three quarters of 13–18 year olds and over half of 19–29 year olds bringing their phones into their bedrooms and using them while they are trying to go to sleep, according to a National Sleep Foundation poll in 2013.

Using screens in the bedroom has several effects, the most recently discovered is the release of blue light, a similar frequency to that of daylight. This light is recognized by our brains and may delay production of melatonin (released by our brains to regulate sleep patterns, often referred to as the ‘sleepy’ hormone) by interrupting our body’s circadian rhythms, the 24 hour cycle of mental, physical and behavioural changes that can be influenced by a many factors, including light.

Switch off your phone before bed and you’ll be on your way to a better night’s sleep. Using a phone makes your mind more alert and studies have shown that this is linked to poor quality sleep. Those that text in the hour before going to bed are found to be less likely to report getting a good night, and more likely to wake up feeling un-refreshed. Not to mention the unwelcome phone calls that wake you up in the middle of the night, giving you broken sleep and a groggy attitude the next morning. If anything, for the sake of your family and co-workers, turn your phone off at night.

Do you use your phone at night? If so, why not try switching off for half an hour before bedtime and see if it helps you get a better night’s sleep. Check out writer Verity’s article on aromatherapy for insomnia, too.

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