Scientists and science students are taking an increasing interest in communicating their research to the public. Mo is a neuroscientist with a popular blog, Neurophilosophy, which collects the most interesting finds in neuroscience and presents them in accessible ways. We asked him to write a short piece for Dream Lab on the function of sleep and its relation to memory – a topic especially interesting to students!
‘We spend approximately one third of our lives asleep, but the exact function of what Edgar Allan Poe called “those little splices of death” has long eluded researchers. In recent years, though, numerous studies have provided evidence that sleep is essential for the consolidation of newly formed memories.
Some of these studies involve presenting two groups of participants with a list of words to memorize. One group is then told to get a good night’s sleep, while the other is made to stay awake. When asked to recall the word list the following day, those participants who slept are found to perform consistently better than those who don’t. The same appears to be true for other forms of memory, such as learning a sequence of finger movements (a form of motor learning). And it is not just long periods of sleep which enhance memory formation – day-time power naps have been shown to have the same effect.
Conversely, sleep deprivation has been found to have an adverse effect on memory. In one recent study, volunteers were first asked to learn a word list; later on, they were shown the same list, but unbeknownst to them, the researchers had added some new words. When asked to recall whether each of these words was present in the first. Sleep-deprived participants gave more false responses than those allowed to sleep. Intriguingly, the false memories induced by sleep loss were reduced by caffeine – sleep-deprived participants who drank a cup of coffee before the recall trial produced 10% fewer false responses than those who did not.
How sleep enhances memory is unclear. Memory formation is widely believed to be involve the strengthening of synapses, the junctions at which nerve cells communicate with one another. It was long thought that the brain rests during sleep, but this is not the case. While apparently off-line, it buzzes with activity, and in fact is more active in sleep than it is during waking hours. This may be because the brain is replaying the day’s experiences, by activating the pathways which encode them. In so doing, it may also be strengthening the appropriate connections, and facilitating the transfer of memories from the parts of the brain where they are formed to those involved in their long-term storage.’
See Mo’s blog for more topics related to the brain and science research.