Empathy and emotional regulation are considered important in social interactions. The relationship between sleep and higher order neurological functions connected to social interactions is poorly understood and results have been inconclusive. Aims: The aim of this study was to investigate how total sleep deprivation affects empathy for pain in others and emotional regulation through self-rated unpleasantness scores and fMRI activity in predetermined regions of interest. Material and Methods: In

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... a cross over design with one night of total sleep deprivation and one night of full sleep, 18 healthy young participants were instructed to downregulate or maintain emotional response to 48 images of hands or feet in painful or non-painful situations followed by ratings of unpleasantness on a scale from 0-100, while functional images were acquired. Results: Unpleasantness scores showed a significant increase when comparing pain to no-pain stimuli (13.4 [11.6 – 15.2], p < 0.00001) and a significant decrease in unpleasantness from pain stimuli following sleep deprivation (-4.8 [-8.34 – -1.25], p = 0.0079). fMRI results demonstrated a significant increase when comparing pain vs no-pain stimuli in the anterior midcingulate cortex (T =2.52 [0.17 – 2.18], p <0.024) as expected. No significant functional outcomes were seen in the anterior insula, lateral orbitofrontal cortex, anterior midcingulate cortex or dorsolateral prefrontal cortex when comparing the full sleep to the sleep deprived condition. Conclusions: This study indicate that sleep deprivation causes less subjective empathy for pain in others, however without functional correlates. Future studies should combine larger sample sizes with total sleep deprivation interventions.