Itâ€™s well-established that sleep helps with problem solving. What has not been established is what part of sleep assists and how a new study may have the answers. Subjects did a memory test and a creativity test in the morning and then again in the afternoon. In between, some subjects had â€œquiet timeâ€, while others slept without dreaming and the rest and went into REM (dream) sleep. Only the group that went into REM showed any change: they did 40 per cent better on their creativity tests. It seems REM sleep causes changes in the levels of cholinergic and noradrenergic neurotransmitters in the brain and this makes new linkages between previously unlinked networks of neurons, which in turn enhances the integration of unassociated information for creative problem-solving. An iron-clad argument for a two-hour nap at work, wouldnâ€™t you say?