Until recently, dreaming has been a mystery over which we all ponder, but our research in the Swansea University Sleep Laboratory has begun to shed some light on this fascinating phenomenon. The study, which was discussed at the British Science Festival on 9 September, revealed a link between daily events and the dreams we experience, examining what happens when we consciously make links between our waking lives and our internal adventures, and even links dreaming to memory.
So, is dreaming a meaningless quirk or does it play an essential role in how human beings process memories?
Firstly, for the scientific study of dreaming, we investigate how waking life events are incorporated into dreams. This includes what the time course of the appearance of such events into dreams is, and whether or not such dream content can be matched to brain activity during sleep. In a recent study participants kept diaries of their daily lives and later compared them to their dream reports collected from different stages of sleep in the sleep lab. Importantly, events from waking life were not only incorporated into the dreams of the following night, but there was also a delayed incorporation, termed the ‘dream-lag’, where events are referred to in dreams five to seven days after they have occurred. Work led by Elaine van Rijn has shown that the dream-lag is more likely to happen for personally significant events, possibly showing that five to seven nights of sleep are needed to process recent important information.
A second line of research looks into how sleep can help stabilize and improve memories of newly learned material, such as words or stories. Work led by Elaine van Rijn has shown that a night’s sleep has a beneficial effect on memory for Welsh words, where these were learned by English-speaking newcomers to Wales, and that the improvement in memory across a period of sleep was related to how much the person values the Welsh language. In other words, the value one places on the material being learned seems to affect how the brain processes that material when one is asleep.
Work led by Alex Reid has looked into memory for emotional stories and photographs across a two hour period during which the person either sleeps or remains awake. Again, sleep was found to be beneficial to memory, and we are now looking at whether the physiology of sleep is related to these improvements in memory. In future studies, we plan to see if the memory advantages conferred by sleep are also found in populations of older adults.
Our third line of research addresses what happens when the person who has had a dream discusses its content and considers how it relates to their recent waking life. Work led by Chris Edwards has shown that more insight is obtained about waking life from working in this way with a dream than from working with a daydream or discussing a recent waking life event. We are looking into whether the metaphors in dreams that depict waking life issues can be a source of personal insight. The findings show that it may be beneficial to discuss dream content with others, and we relate this benefit to findings that dreams are more likely to refer to recent emotional events in one’s life than to non-emotional or unimportant events.
The above lines of research address how sleep improves memory and whether the dreams that occur during sleep are related to the memory functions of sleep. There is still considerable debate on whether dreams are related to memory functions during sleep, or whether dreams are purposeless meanderings of the mind.
At the British Science Festival on Friday 9 September, we discussed the relationship between sleep, dreaming and memory consolidation, and shared dreams in an interactive workshop.