Wednesday 18 July 2018

Hit the snooze button: why dreams are vital

As modern life interferes with quality rest, new research reveals it's not just how much you sleep, but what you do with it that counts. Kathy Donaghy reports

Rest assured: REM sleep is vital for the retention of memories
Rest assured: REM sleep is vital for the retention of memories

You know that feeling when a powerful dream you're having is interrupted and, try hard as you might, you can't just jump back in? With the alarm going off early for work, children to look after and busy lifestyles to lead, potent dreams are regularly broken. This may mean we are depriving ourselves not just of valuable sleep time, but of deeply powerful dream time that can boost our mental function in a myriad of ways.

New research shows that our dreams do much more than taking us on a magical night-time mystery tour. It shows that rapid eye movement (REM) sleep - the time when we have powerful dreams - is vital to learning and creativity, and promotes a healthy mind in a variety of ways.

Some of the biggest effects of REM sleep seem to be around memory. Researchers at McGill University in Montreal studied what a lack of REM sleep does to mice. By depriving the hippocampus, the part of the brain where memories are stored, of the brainwaves generated during this type of sleep, the team showed that mice couldn't consolidate memories about tasks they had learned the day before.

But when they disrupted the hippocampus in a similar way when the mice were awake or in non-REM sleep, they found the animals were able to form memories as normal.

At Harvard Medical School, researchers are looking at how our dreams help us make choices. "They are part of the mechanism the brain has to choose amongst potential interpretations," says Professor Robert Stickgold from the school's division of sleep medicine. This would explain why our ability to make a decision when we simply "sleep on it" seems easier.

Dr Seamus Linnane, Consultant Respiratory Physician at Beaumont Hospital in Dublin, says we are only beginning to fully understand the importance and functions of REM sleep.

Dr Linnane, who treats people with respiratory sleep issues, explains that while REM sleep accounts for 20pc of our total sleep, it's an important component.

"I like the notion of describing sleep as descending through different layers, like you're diving down into water and REM sleep would be like settling on the bottom where it's calm," says Dr Linnane.

He says when he conducts sleep studies on patients and sifts through the graph showing their different stages of sleep, you can clearly identify them.

"People tend to have a cycle of sleep and it's usually two hours. That two hours gets repeated so you have four or five sleep cycles in a night. The REM sleep tends to be at the end of the cycle. As you go through the night, your REM cycle increases. So if you're skipping the second half of your sleep, you're missing out on REM," he says.

Dr Linnane says people who are denying themselves REM sleep would have poorer quality concentration and would not be consolidating their memories.

"It's such an integral part of human experience and yet there are gaps in our understanding. As people's understanding of the importance of sleep to their lives grows, they are taking sleep more seriously.

Read more: Five ways to boost your dream sleep

"I subscribe to the notion of sleep hygiene - it's a really useful concept. You have to decide for yourself the number of hours of sleep you need - for most people it's seven or eight hours.

"Getting up needs to be consistent across the week and in that golden hour before sleep, you need to ensure you're not stimulated by exercising late or having a large meal.

"It's important to allow yourself the opportunity to 'unplug'," says Dr Linnane. Dr Mark Rowe, a Waterford-based GP with a huge interest in sleep, says he believes sleep problems are epidemic. "Research shows that 20pc of adults are getting less than six hours of sleep a night. Less than six hours is very bad for your health," he says.

With less than six hours a night, he says the impact on your physical health is serious, with the long-term risk of heart attack going up by 200pc and putting you at increased risk of long-term memory loss, diabetes and stroke.

"When you're sleep deprived, you're living in your emotional brain. There's a fine tuning between our logical brain and our emotional brain, which stops our fears running away with us. When you're sleep deprived this fine tuning gets impaired and you're living on fight or flight, leaving you feeling anxious and stressed," says Dr Rowe, author of The Prescription for Happiness.

He says sleep is characterised by four different stages: stage one is where we begin to doze off, stage two is falling into a deeper sleep while stage three is deep sleep or what is called as restorative sleep. After that comes REM sleep.

"We don't understand all of it but REM is very important for emotional processing. It allows us to extinguish fears and anxiety as we get to replay them. When people don't get enough sleep, they don't get to deal with these fears. It's also very important for consolidating memory," he says.

Dr Rowe says alcohol is a "disaster" when it comes to affecting our sleep. And while he says at first people may feel relaxed if they have a couple of glasses of wine in the evening, the effect of the alcohol on the body over the course of the night will mean your sleep is disrupted and you wake more often.

"We know it damages REM sleep. People who binge drink will often feel anxious the next day. Alcohol affects all the stages of sleep, but the breakdown of alcohol in the body, which produces formaldehyde, is impacting directly on REM. The best thing you could do (to improve your sleep) is to cut out alcohol," he says.

Dr Rowe says often sleep is not valued in our list of priorities and yet it's fundamental to everything we do. "Giving yourself more sleep is an investment in your well-being." He believes the culture around sleep where we throw around comments like "I'll sleep when I'm dead" and equate sleep with laziness is starting to change, but we have a long way to go.

Irish Independent

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