We’ve been looking at lucid dreams in the last two newsletters – that strange state of consciousness in which dreamers become aware that they’re dreaming, and can direct their experience. The first looked at a study linking meditation with lucid dream (LD) frequency.
The second examined the practice of Tibetan dream yoga, which assists adepts to achieve the “clear light” of non-dual awareness.
This week, let’s take a peek under the bonnet and see what’s happening in the brain. The first paper to investigate neural correlates of LD was published in 2012 in the self-explanatory SLEEP journal (sample headline from current issue: Influence of Mid-Afternoon Nap Duration and Sleep Parameters on Memory Encoding, Mood, Processing Speed and Vigilance.)
Led by German PhD Martin Dresler, whose name pops up on a number of LD papers, the team recruited four experienced lucid dreamers – having at least one such experience each week – and used an fMRI machine to scan their brains. The subjects, the authors write, also had “the perceived ability to sleep in a MRI scanner environment, ie, in a fixed supine position during loud noise”.
They’re not kidding about the noise. For those readers who haven’t had an MRI scan, this is what they sound like.
Still, the four subjects, aged 27, 29, 31 and 32 (who’d lucid dreamed for four, 20, 17 and five years respectively) were told to communicate having reached lucidity during the dream by moving their eyes left-right-left-right, clenching their left hand for about 10 seconds, give the LRLR signal again, clench their right hand, etc. (People in a LD can communicate by blinking their eyes.)
How did they do? In an outcome possibly linked to the “loud noise”, while all four managed to fall asleep, only one subject managed two long and stable lucid dreams (at 6.25am and 5.45am during REM sleep, which is most likely in the early morning). All four reported reaching lucidity, but only he managed to give the LRLR signal, “rendering our data a case study”, write the authors.
The colour-coded clusters above show significantly activated brain areas during LD for our special guy. Normal dream sleep – REM sleep – sees neural activity increase in regions such as the brain stem, thalamus and amydala, with the likes of precuneus deactivated.
But lucid dreaming sees higher cognitive capabilities regained, and usually switched-off regions working again. The authors note that there was activation in the right dorsolateral prefrontal cortex – the top left blob in B – which is associated with thinking about thinking.
The biggest LD activation was seen in the precuneus – which I think is the top left blob in A – which has been linked with self-consciousness. That would also tie in to the difference between normal dream sleep’s mental imagery driving events, and lucid dreaming’s sense of agency.
Further activation was found in two areas associated with visual processing. This, the authors say, is in line with lucid dreamers reporting “an exceptional brightness and visual clarity of the dream scenery”.
As for limitations, the biggest is the sample size of one, making drawing conclusions dicey, which lets me post this old favourite.
Next week: testing a super-powered group who had a lucid dream at least every other night.