The emotional brain and sleep: an intimate relationship.

Research findings confirm our own experiences in life where daytime events and especially emotionally stressful events have an impact on sleep quality and well-being. Obviously, daytime emotional stress may have a differentiated effect on sleep by influencing sleep physiology and dream patterns, dream content and the emotion within a dream, although its exact role is still unclear. Other effects that have been found are the exaggerated startle response, decreased dream recall and elevated awakening thresholds from rapid eye movement (REM)-sleep, increased or decreased latency to REM-sleep, increased REM-density, REM-sleep duration and the occurrence of arousals in sleep as a marker of sleep disruption. However, not only do daytime events affect sleep, also the quality and amount of sleep influences the way we react to these events and may be an important determinant in general well-being. Sleep seems restorative in daily functioning, whereas deprivation of sleep makes us more sensitive to emotional and stressful stimuli and events in particular. The way sleep impacts next day mood/emotion is thought to be affected particularly via REM-sleep, where we observe a hyperlimbic and hypoactive dorsolateral prefrontal functioning in combination with a normal functioning of the medial prefrontal cortex, probably adaptive in coping with the continuous stream of emotional events we experience. (c) 2010 Elsevier Ltd. All rights reserved.