During REM sleep, where most dreaming takes place, your eyes move around but it’s never been clear exactly why. A new study just published online by neuroscience journal Brain suggests that they are looking at the ever-changing dream world.
The first question you might ask is how the researchers knew what the dreamers were looking at. To study this, the project recruited people with a condition called REM sleep behaviour disorder who lack the normal sleep paralysis that keeps us still when we dream.
In other words, people with REM sleep behaviour disorder act out their dreams. We’ve discussed the fascinating condition before as it gives an outside view to the inner dream life of the affected person.
In this case, the researchers, led by neuroscientist Laur√®ne Leclair-Visonneau, used electrodes to monitor the eye-muscle movements of 56 patients with REM sleep behaviour disorder and 17 healthy controls in a sleep lab, while also videoing their night-time movements.
The research team initially looked to see if there was a major difference in rapid eye movements between people with the condition and those without. They found that the groups were statistically indistinguishable – meaning that the sleep disorder wasn’t likely to be affecting the eye-movements themselves.
Knowing that REM eye-movements were not abnormal in people who acted out their dreams, the team then looked at the video and picked out where patients completed a ‘goal directed action’ while dreaming – such as picking up a dream object or reaching out to touch something.
By synchronising the videoed actions with the eye muscle recordings during REM sleep the researchers found that the eyes were fixed on the dream target 90% of the time.
In other words, when the eyes move during REM sleep they are looking at something in the dream world.
The eyes seem genuinely to be a bridge between the land of dream consciousness and waking life.
Link to PubMed entry for REM and dreaming study.