Table 1.

Characteristics of the included articles

Author(s)	Country of study	Type of study	Non-REM parasomnia described	Number of participants in study with nREM parasomnia	Study aim	Main outcome
Schenck et al (1991)	USA	Cohort study	Sleepwalking Sleep terror SRED	16	To describe polysomnographic correlates of SRED in 19 adults with nocturnal behavior including eating as well as associated sleep-related injury over a 5-year period.	The study concluded sleepwalking, periodic movements of sleep, and triazolam abuse are etiologic categories of sleep-related eating.
Zadra and Nielsen (1998)	Canada	Case report	Sleep terror	1	To describe the topographical EEG mapping study of a patient with sleep terrors, examining one-minute sections of the EEG tracing immediately prior to onset of sleep terror episodes.	The study demonstrated more total and delta power in central and frontal areas compared to control (normative data) and proposed these were possibly related to underlying slow-wave sleep mentation, which may sometimes trigger episodes of sleep terror.
Hartman et al (2001)	UK	Cohort study	Sleepwalking Sleep terror	22	To examine the possibility of underlying protective dissociative process in sleepwalking and night terrors.	They identified 6 patients with a history of trauma and 2 of them demonstrated possible underlying dissociative process with trauma-related sleep mentation content.
Lauerma (2003)	Finland	Case report	Sleep terror	1	To report a case of sleep terror which was proposed to have been related to drug-induced dissociative states in a man following prescription of fencamfamine.	Polysomnography demonstrated evidence of arousals from slow-wave sleep.
Shapiro et al (2003)	Canada	Case reports	Sexsomnia	10	To present case reports describing sexsomnia in 10 adults, some of whom had medico-legal issues resulting from episodes of sleep-related sexual behavior.	The report highlighted similarities as well as distinct differences between sleepwalking and sexsomnia including prominent automatic arousal, restricted but specific motor activities, and associated dream mentation.
Oudiette et al (2009a)	France	Cohort study	Sleepwalking Sleep terror	42	To explore dreamlike mentations during sleepwalking and sleep terrors in adults.	The study concluded complex mental activity takes place during slow-wave sleep, and sleepwalking may represent a form of acting out of mentation.
Pillmann (2009)	Germany	Case report	Sleepwalking	1	To describe a case report of complex dream-enacting behavior in a 26-year-old male patient with sleepwalking	Psychosocial factors and possible worsening of asthma were thought to be contributory factors leading to increased sleep fragmentation.
Brion et al (2012)	France	Cohort study	Sleepwalking sleep terror SRED	36	To compare clinical, sleep and eating behavior measures in patients with SRED against sleepwalkers and controls.	The study concluded the patients with SRED, possibly due to their underlying or pre-existing eating behavior, have somehow specialized their sleepwalking behavior to sleep-related eating behavior.
Perogamvros et al (2012)	Switzerland	Case report	SRED	2	Reported 2 cases of SRED with PSG, psychometric assessment and dream diary.	Study concluded there is possibly an active reward system during sleep, which could be implicated in the manifestation of SRED.
Mwenge et al (2013)	France	Case report	Sleepwalking	1	Reported the case of a 33-year-old woman who monitored her nighttime behavior for 36 days using a home camera.	She reported dreamlike mentation that suggested evidence of dream-enactment. Finger pointing behavior was observed, which demonstrated possibility of visual hallucinations or residual images from dreams projected into the bedroom.
Uguccioni et al (2013)	France	Cohort study	Sleepwalking Sleep terror	32	Compared dream-enacting behaviors in patients with sleepwalking and sleep terrors to dream-enactment in rapid eye movement sleep behavior disorder.	They demonstrated more misfortunes and disasters but less human and animal aggression when compared to RBD group. The differences in the response to threat observed in the dream contents in this study is thought to be one of the many ways dreaming in NREM sleep differs from dreaming in REM sleep.
Szucs et al (2014)	Hungary	Cohort study	Sleepwalking	9	To retrospectively evaluate 13 patients referred to a sleep clinic.	Concluded that, given most cases of sleepwalking are not as extreme as the cases described in their study, violent somnambulism might be a distinct NREM sleep-related overlap parasomnia.
Dubessy et al (2017)	France	Cohort study	Sleepwalking Sexsomnia	17	Described patients with sexsomnia and compared clinic and sleep measures with those of sleepwalkers and controls.	The authors concluded there was male predominance of sexsomnias and pointed out possibility of a continuum with sleepwalking on one end and sexsomnia on the other.
Iqbal et al (2017)	USA	Case report	Sleep terror	1	Described a 21-year-old female with history of anxiety and depression.	This case highlighted the unusual presentation of what the authors concluded were hypnopompic hallucinations in stage 2 of NREM sleep.
Gnoni et al (2020)	UK	Case report	Confusional arousal	3	Described 3 rare cases of nihilistic delusions (Cotard le délire de negation) in which affected individuals described complete or partial loss of their perception of body and existence	Proposed Cotard parasomnia and its associated phenomenology may be the product of incomplete, fluctuating activation and switching between the salience network and the default mode network.
Rocha and Arnulf (2020)	France	Case report	Sleepwalking Sleep terror	1	Reported a case of dream-enactment in a 37-year-old woman with a history of sleep terrors and sleepwalking.	The unique links of the dream content with reality and the recall of events led the authors to conclude NREM parasomnias can also be dream-enacting behaviors.

*Abbreviations: SRED – sleep-related eating disorder; PSG – polysomnography; NREM – non rapid eye movement; RBD – REM sleep behavior disorder.