Episode 19
You’ll Never Believe The Dream I Had Last Night!
What is the deal with dreams?
In this episode, I discuss some of the quirks and perks of dreams.
If you don't always recall your dreams, don't feel bad! Studies show that when prompted every single morning, individuals may recall only about 3 dreams per week, but about 5% can't recall a single dream all week.
During rapid eye movement (REM) sleep, the overall electrical activity of the brain more closely resembles wakefulness compared to any other stage of sleep; however, imaging studies paint a different picture. Several regions of the brain are cranked up, including the amygdala (the emotional alarm center of the brain) while other regions are turned down quite a bit, including several areas of the prefrontal cortex. This is why we tend to have strong emotionality to dreams and why they can be so bizarre - the parts of the brain that would normally rationally evaluate experience and scrutinize whether its realistic or not are offline!
The brain uses this opportunity of REM sleep dreaming for emotional processing. Your brain takes a new memory, puts it in a blender, and takes the resulting memory bits or subunits and recombines them with other older memory subunits to bake a memory meatloaf. This helps strengthen associative memory, but also allows any emotionally startling memories to be processed in a new context. Like Pavlovian conditioning discussed in Episode 16, when your brain repeatedly combines parts of an upsetting memory with other non-upsetting memory subunits, the strength of the association between that original trigger and the resulting strong emotion begins to dwindle, since that original trigger may now have several other new associations, softening the strong emotional response.
But the context of the dream matters, specifically, the neurochemical environment matters. Normally during REM sleep, levels of stress hormones, including norepinephrine (a neurotransmitter just like adrenaline) are at their absolute lowest. However, when there is disruption of normal REM sleep, which is nearly guaranteed with sleep disordered breathing, levels of these stress hormones are dramatically higher - since it is the surge of adrenaline and the sympathetic nervous system that wakes sleepers in order to allow them to take a normal healthy breath again.
When REM dreaming is muddled by the higher stress environment due to the body's response to sleep apnea, rehearsal of stressful memories and strong emotions can actually lead to the strengthening (rather than dampening) of these strong emotional memories.
The result? Individuals with sleep apnea are about 2.5x more likely to develop depression and about 3x more likely to develop anxiety disorders. And this REM disturbance is thought to be one of the main drivers leading to PTSD after a traumatic event - since the brain lost the opportunity to process the traumatic event in safe simulation of REM sleep. Thankfully, treating sleep disordered breathing in those with PTSD has been shown to lead to a significant improvement in overall symptoms, and especially in reducing the frequency of nightmares, with some studies demonstrating nightmares eliminated entirely by treating sleep apnea.
Sweet dreams!
