Sleep and creativity

The majority of studies on sleep creativity have shown that sleep can facilitate insightful behavior and flexible reasoning, and there are several hypotheses about the creative function of dreams. On the other hand, a few recent studies have supported a theory of creative insomnia, in which creativity is significantly correlated with sleep disturbance.

In a study on cognitive flexibility across the sleep-wake cycle, researchers discovered that when woken from REM sleep, participants had a 32% advantage on an anagram task (when compared with the number of correct responses after NREM awakenings). This was consistent with the hypothesis that due to the lack of aminergic dominance in REM sleep, this particular sleep state is highly conducive to fluid reasoning and flexible thought. Interestingly, participant performance after awakening from REM sleep was not better than participants who stayed awake, which indicates that in REM sleep, there is an alternative (but just as effective) mode of problem solving that differs from the mechanism available while awake.

Participants in a study were asked to translate a string of digits using two simple rules that allowed the string to be reduced to a single digit (number reduction task). Out of three groups of participants (those who slept, those who stayed awake during the day, and those who stayed awake during the night), participants who got eight hours of sleep were two times as likely during retesting to gain insight into a hidden rule built into the task.

Some participants in a study went 32 hours without sleep while the control participants slept normally. When tested on flexibility and originality on figural and verbal tests, the sleep-deprived participants had severe and persistent impairments in their performance.

Under hypnotic-induced sleep, participants were much more likely to produce paraphrases of jokes that they had heard before and to spontaneously create new jokes (when compared with their performance while awake).

Recent studies have also shown that sleep not only helps consolidate memory, but also integrates relational memories. In one study, the participants were tested to see if sleep helped in this aspect (Ellenbogen et al., 2007, as cited in Walker, 2009). The subjects of the experiment were taught five "premise pairs", A>B, B>C, C>D, and D>E. They were not aware of the overall hierarchy, where A>B>C>D>E. The subjects were split into 3 separate groups. The first group was tested 20 minutes after learning the pairs, the second was tested 12 hours later without sleep, and the third was tested 12 hours later with sleep in between. The groups were tested in both first degree pairs (A>B, C>D, etc.) and 2nd degree pairs (A>C, B>D, or C>E). The results were that with the first degree pairs, the first group only performed at around chance levels, and the second and third groups had significantly better performances. With the 2nd degree pairs, the first group still performed at around chance levels, and the second group performed at about the same level as in the 1st degree pair test. However, the third group performed even better than before, gaining a 25% advantage over the group without sleep. The results of this study showed that sleep is a significant factor in integrating memories, or gaining the bigger picture.

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