I’ve asked the question whether it is possible to feel pain while asleep before. It led to some great discussion, as well as a fascinating first hand report. A recent paper in Sleep (I love these simple, unambiguous journal titles) reported on an experiment that asked known somnambulists about their experiences of pain. A press release from the American Academy of Sleep Medicine detailed some intriguing results:
Sleepwalkers feel no pain, remain asleep despite suffering injuries
“Among sleepwalkers with at least one previous sleepwalking episode that involved an injury, 79 percent perceived no pain during the episode, allowing them to remain asleep despite hurting themselves.
“Our most surprising result was the lack of pain perception during the sleepwalking episodes,”… “We report here, for the first time, an analgesia phenomenon associated with sleepwalking.”
…one patient sustained severe fractures after jumping out of a third-floor window while sleepwalking but didn’t feel the pain until after waking up later in the night. Another patient broke his leg during a sleepwalking episode in which he climbed onto the roof of his house and fell down, but he didn’t wake up until morning.”
The phenomenon we collectively call ‘sleep’ actually represents a range of altered states of consciousness – in some we can have terrifying experiences while being paralysed, and yet in others we can behave and function at high levels (jump out of windows and climb on to roofs) but not experience pain despite serious injury – and quite possibly not have any subjective experience at all. This is what makes the question of pain while sleeping so captivating to me – it provides a tantalising glimpse into the issues at the very heart of pain – consciousness and subjective experience.