Patterns of hemispheric lateralization in dream recallers and non-dream recallers

Eighteen right handed females reporting 6 or more dreams per week on a home dream and sleep diary (Dream Recallers: DR), and 11 reporting 1 or 0 dreams per week (Non Dream Recallers: NDR) drawn from a sample of 233 college students, were individually tested on two tasks assessing the hemispheric lateralization of visuo-constructive and verbal-semantic functions. NDR showed a significant degree of hemispheric asymmetry of both visuo-constructive (right asymmetry of both visuo-constructive (right hemisphere advantage) and semantic (left hemisphere advantage) functions. DR showed no hemispheric advantage on both tasks. The two groups of subjects did not differ in mean daily amount of sleep time. In keeping with previous studies showing that NDR have an imbalance of interhemispheric activation upon REM awakenings, results from the present research suggest that DR and NDR can be characterized by a different pattern of hemispheric lateralization of cognitive skills. This finding may stimulate further research aimed at evaluating both the possible existence of differences in the lateralization of functions not considered in this study and the concomitance of REM sleep dependent differences in balance of hemispheric functioning.