It was in 1953, sleep researchers identified – for the very first time – distinct episodes during sleep associated with dreaming. Owing to what they described as a ‘hurricane’ of ocular activity associated with this phase, they called it rapid eye movement sleep or REM for short. Yet remarkably, just over 70 years on, there is still no consensus over the function of REM or why we dream.

In a lunchtime talk, biology teacher Dr Henry Nicholls asked the Year 11 Colloquium to suggest possible functions of REM and within the space of ten minutes they’d identified most of the competing theories.

Observations of newborn babies shows that not only do they sleep for around 16 hours a day (albeit in fragments that bear no relation to the axial rotation of the earth), they also spend almost half this time in REM, strongly suggesting that sleep and especially dreaming sleep must play an important role in brain development. Supporting this idea, there are several recent studies that provide clear evidence of “synaptic pruning” during REM, a process analogous to editing that involves strengthening the connections between some neurons and weakening or erasing others. Another possible function of REM and dreams is as an engine of creativity.

There are several well-known examples of the Eureka-like power of dreams, including August Kekulé’s vision that cracked the structure of benzene, Dimitri Mendeleev’s brilliant periodic table of the elements and Paul MacCartney’s Yesterday, one of the Beatles’ best known singles and one of the most covered songs in the history of recorded music.

Following a discussion about dream content, the Year 11s anticipated a fascinating hypothesis that suggests dreams might provide the brain’s way of rehearsing how to respond to threatening scenarios, a safe, virtual world in which there is no danger of coming to harm. This idea has the merit of explaining why dreams are so visual, as does the latest hypothesis to explain the evolution and persistence of REM sleep proposed in 2021. The so-called “defensive activation theory” argues that by activating the visual cortex periodically throughout the night, dreams could help this region of the brain “to defend its territory against takeover of other senses.”

The group thought a little about Consciousness last term, a field in which dreams are sometimes referenced but often in passing. Maybe that will change….