Why sleep really is the great healer

4 minute read

If everything does look less terrible in the morning, it’s thanks to noradrenaline and friends.

It can take a while for science to nail down things we all know and have known for centuries, if not millennia.  

If, for example, you told Shakespeare that sleep heals emotional distress, he’d probably say “There needs no ghost, my lord, come from the grave to tell us this”, roughly his equivalent of “No shit, Sherlock”.  

He did, after all, put these words into the mouth of a horrified Macbeth, right after his spot of cheeky regicide, when a ghostly voice has cursed him with never sleeping again:  

… the innocent sleep, 
Sleep that knits up the ravell’d sleeve of care, 
The death of each day’s life, sore labour’s bath, 
Balm of hurt minds, great nature’s second course, 
Chief nourisher in life’s feast, – 

Macbeth would probably have carried on like this for a while with even more metaphors for how good sleep is when you’re a bit het up if his wife hadn’t told him to snap out of it and go wash his hands. 

The Back Page will also now attempt to snap out of it and get to the point. If we’re straying down a tangent it’s thanks to a particularly fractured night of sleep, which makes the topic feel acutely relevant.  

A recent perspective piece in Nature proposes a model for exactly how sleep – not just any old nap but a decent chunk of REM – soothes a distressed mind.  

An international team including the Woolcock Institute’s Dr Rick Wassing looked at two decades’ worth of sleep research across neurobiology, neurochemistry and clinical psychology.  

They concluded that the way certain neurotransmitters are regulated in various sleep modes permits the brain to reorganise the synaptic connections that form memories without activating the autonomic nervous system and its fight-or-flight response to upsetting thoughts.  

During REM sleep noradrenaline and serotonin levels are very low, while acetylcholine is low during non-REM sleep. These outages “provide a unique window of opportunity for plasticity in neuronal representations of emotional memories that resolves the associated distress”. 

When we are awake, or when we fail to get proper sleep, there is no opportunity to process and take the edge off emotional memories without causing our hearts to race, cheeks to flush and all the other exciting ways our amygdalas can make our distress tangible.  

How to fix bad sleepers, well, there’s the rub.  

There’s scope to research drugs that target these mechanisms, Dr Wassing says, although it’s not as simple as, say, subduing the noradrenergic system for the duration of sleep as it has to be active during non-REM sleep.  

Dr Wassing does not put much faith in cognitive behavioural therapy for insomnia: “The insomnia patient after CBTI is not necessarily a good sleeping individual, they still have some sleep disturbances but CBTI is enabling them to better deal with them.” 

In the meantime, the model helps explain bad mental health stemming from insomnia, the authors say: “The model generates testable hypotheses for how failed sleep-dependent adaptation to emotional distress is key to mental disorders, notably disorders of anxiety, depression and post-traumatic stress with the common aetiology of insomnia.” 

“We know that with insomnia or other sleep disorders where people wake up from sleep a lot, we see an increased risk of developing mental health problems,” Dr Wassing says.  

“Our hypothesis would be that these awakenings from sleep lead to the fact that the noradrenergic system is not shut down for long periods of time (in fact, they might actually show enhanced activity) and that’s why these people might not be able to regulate emotional memories.” 

Macbeth didn’t keep a sleep journal, but if he did indeed sleep no more after killing Duncan, that could explain quite a lot: his hallucinations, paranoia, affectless reaction to his wife’s death and rather bleak conclusion that life is “a tale told by an idiot”.  

Maybe he should have hit the weird sisters up for a sleep potion instead of more cryptic and misleading prophecies.  

Send story tips/eye of newt/NoDoze to penny@medicalrepublic.com.au

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