To Wake, Perchance to Remember (Your Dreams)

My morning coffee is often accompanied by a series of text messages from my sister relaying her latest bizarre dream. The latest installments the Annals of Sisterly Nighttime Hallucinations have featured piano sheet music composed by threading different colors of cross-stitch floss, a dryad guilt-tripping her for standing on rotten acorns, being left to be devoured by wolves summoned with battered yellow lunch trays, acorns that slow down time, and a truck carrying other trucks that tipped over in the road requiring a police report. And I can only marvel, not just at the content but at the sheer level of detail, because I am lucky if I remember that I had any dream at all, and have never been able to describe more than a snippet.

Freud, the original dream interpreter, might suggest that my sister has a closer connection with her unconscious mind than I do, or has more wishes pressing for fulfillment (I’m almost curious what he would make of the recurring theme of acorns in my sister’s dreams). But the research I’m talking about today suggests absolutely no differences in personality between those who often remember their dreams and those who rarely do, on a wide range of personality tests – including the Mindful Awareness Attention Scale, which I was naturally excited to see making an appearance. Instead, remembering or not remembering a dream may come down to how active a few key brain areas are while we sleep.

What determines if he will remember his dream? Art by ξωαŋ ThΦt, appear under Creative Commons license.

What determines if he will remember his dream? Art by ξωαŋ ThΦt, appearing through Creative Commons license.

The specific brain regions of interest for remembering our dreams are the temperoparietal junction (TPJ), which is toward the back of the brain where the temporal and parietal lobs of the brain meet (hence the name), and the medial portion of the prefrontal cortex (mPFC), which sits behind our foreheads. I’ve mentioned the mPFC before, because it’s a key player in the “default network“, helping us understanding ourselves and other people; activity here might mean dreamers are figuring out why dream characters are doing what they are doing, creating more story elements that will make a dream more memorable. The TPJ’s job is difficult to pin down precisely, because it seems to have gotten itself involved in figuring out what other people believe (like the mPFC) and altruism and even things going viral online, as well as general awareness of the world around us. Any of these jobs would be helpful to remembering dreams though: more activity here while we dream could help make the story of the dream rich and memorable, or it could mean that we are semi-awake and therefore processing the dream in a way that might be remembered.

Whatever the precise roles turn out to be, we have some good evidence that activity the TPJ and mPFC distinguish those who can entertain the family with crazy dreams stories over breakfast from those of us who can only listen. When healthy but very sleep deprived young men were put in a PET scanner and went to sleep, those who had reported recalling at least 3 dreams a week (the “high recallers”, like my sister) showed more activity in both the TPJ and the mPFC than those who remembered no more than 1 dream a week (the “low recallers”, like me).

These differences in brain activity aren’t just there when we’re dreaming, though; high recallers also have more activity in the TPJ and mPFC when they’re awake (but not when they are in a light and probably dreamless sleep). One explanation for this is that people who remember their dreams are actually a little more awake when they sleep – they wake up more often, or are somehow more aware of the events going on around them (one of the TPJ’s jobs), allowing them to process their dreams in a more memorable fashion. Another possibility is that the TPJ belongs with the mPFC as part of the default network, and people who remember their dreams have a different default state of mind than the rest of us, one that creates a more complex inner world and dreams that are just more memorable, period.

I am currently leaning toward the default network explanation, and not just because it gels so nicely with the simple statement that your brain just works differently (or, as I actually texted my sister, “Your brain is weird”). The night after I first read about the possibility that waking in the night helps you remember your dreams, I happened to wake up from a dream. I was awake enough to think to myself, “I have to tell my sister that I had a dream where the monkey…” and complete the sentence with whatever bizarre monkey activity I thought would be so interesting. But I can’t complete that sentence now, because I cannot remember what on earth that monkey was doing; I don’t really remember the dream, just that moment of being awake and thinking. I take care to caution my students that one personal experience that’s different than what a study says does not invalidate the study, because there are always unique cases, but I’m doubtful that any amount of middle-of-the-night awakenings will be enough to get my dreams to stick. It might take a much more intensive intervention to change my brain’s default setting. In the meantime, I’ll just have to live vicariously though my sister’s remembered dreams.

ResearchBlogging.org
Eichenlaub JB, Nicolas A, Daltrozzo J, Redouté J, Costes N, & Ruby P. (2014). Resting brain activity varies with dream recall frequency between subjects. Neuropsychopharmacology. PMID: 24549103

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