Hand dominance shift during sleep in sexsomnia: a clue to pathophysiology?

To elucidate whether awake handedness in sexsomnia is retained during sleep to uncover potential clues about the underlying neurophysiologic mechanisms.

Participants' and observers' self-reported handedness during sexsomnia events.

Case 1: A 22-year-old right-handed (RH) female with an 8-year history of nocturnal sleep-related masturbatory behavior (SMB) involving the left hand (LH) exclusively. Case 2: A 30-year-old ambidextrous male with SMB involving both hands, but most prominently the LH. Case 3: A 33-year-old RH female with exclusively LH SMB in the setting of acute multiple sclerosis exacerbation with cervical spinal cord and brainstem involvement. Case 4: A 44-year-old RH male with bilateral dream enactment behavior and LH-predominant SMB noted by the bed partner. Case 5: A 59-year-old RH female with a history of multiple system atrophy and rapid eye movement sleep behavior disorder developed a new SMB, noted by the bed partner involving exclusively the LH. Case 6: A 37-year-old RH male with inappropriate sexual behaviors involving the nondominant LH without retention of memory for the events. Case 7: A 17-year-old RH male with polysomnographic evidence of genital manipulation using both hands but predominantly involving the nondominant hand.

We speculate that sexsomnias originate from central pattern generator in the brainstem and spinal cord, as opposed to the cerebral cortex. The lack of involvement of cerebral motor control is further substantiated by amnesia for sexsomnia events. The implications of these data provide fundamental new clues about the mechanism of sexsomnias with critical forensic implications.

Avidan AY, Hasan R, Badami V, Schenck CH. Hand dominance shift during sleep in sexsomnia: a clue to pathophysiology? J Clin Sleep Med. 2025;21(5):937-941.