Research paper Sleep and disruptive mood dysregulation disorder: A pilot actigraphy study R. Delaplace a , S. Garny de La Rivie ` re a,b , M. Bon Saint Come b , H. Lahaye a,b , I. Popov c , N. Rey b , A. Visticot b,d , J.-M. Guile ´ a,b, * a GRAMFC, Inserm 1105, universite ´ Picardie–Jules-Verne et CHU d’Amiens, 80480 Amiens, France b Service de psychopathologie de l’enfant et de l’adolescent, CHU d’Amiens, 80480 Amiens, France c CRC pe ´diatrique, CHU d’Amiens, 80480 Amiens, France d Centre hospitalier, boulevard Georges-Besnier, 62000 Arras, France 1. Introduction In pediatrics, emotional and behavioral disturbances are recurrent reasons for consultation. Interest in these disturbances has grown since they were recognized as a specific syndrome, namely disruptive mood dysregulation disorder (DMDD). This syndrome emerged from discussions about the prepubertal phenotype of bipolar disorder (BD) [1,2] and first appeared in the Fifth Edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) in 2013 [3]. According to the DSM-5, DMDD is marked by temper outbursts manifested verbally and/or behav- iorally that are:  grossly out of proportion in intensity or duration to the context;  inconsistent with the child’s developmental age and the context of the occurrence. A further defining criterion is persistent dysphoric, angry or irritable mood between temper outbursts. The DSM-5 also lists a number of quantitative criteria required for a diagnosis of DMDD: at least three outbursts a week, the occurrence of outbursts in at least two settings (at school, at home, and/or with peers), the presence of outbursts for at least 12 months (and no periods without symptoms lasting 3 or more consecutive months) and an age of onset before 10 years. The condition can be diagnosed in children from the age of 6 and in adolescents. A diagnosis of DMDD cannot coexist with BD or oppositional defiant disorder (ODD). The clinical description given in the DSM-5 does not include excitability symptoms that are associated with attention deficit Archives de Pe ´ diatrie xxx (2018) xxx–xxx * Corresponding author. Service de psychopathologie de l’enfant et de l’adoles- cent, CHU d’Amiens, boulevard Lae ¨ nnec, 80480 Amiens, France. E-mail address: J.-M.Guile ´ ab *guile.jean-marc@chu-amiens.fr (J.-M. Guile ´). A R T I C L E I N F O Article history: Received 2 September 2017 Accepted 20 May 2018 Available online xxx Keywords: Disruptive mood dysregulation disorder Actigraphy Sleep Child A B S T R A C T Objective: To explore the clinical characteristics and motor activity profile during sleep periods of children and adolescents presenting with disruptive mood dysregulation disorder (DMDD). Method: Twenty-one youths (mean age  standard deviation, 11.7  3 years) wore a wrist actigraph for 9 consecutive days (including both school days and non-school days), to measure sleep parameters: sleep latency, sleep efficiency and the number and duration of periods of wakefulness after sleep onset (WASO). We divided the night-time actigraphy recording sessions into three sections and compared the first and last thirds of the night. Results: All the study participants had a psychiatric comorbidity (primarily attention deficit hyperactivity disorder, depressive disorder or anxiety disorder). On non-school days, bedrest onset and activity onset were shifted later by about 1 h. There was no significant difference between school days and non-school days with regard to the total sleep time. Sleep efficiency was significantly greater on non-school days. Sleep was fragmented on both school days and non-school days. The mean number of episodes of WASO was 24.9 for school days and 30.9 for non-school days. Relative to the first third of the night, we observed a significantly greater number of episodes of WASO during the last third of the night, a period associated with a larger proportion of rapid eye movement (REM) sleep. Discussion: Sleep appeared to be fragmented in the study population of youths with DMDD. The greater frequency of WASO in the last third of the night points to a possible impairment of the motor inhibition normally associated with REM sleep.  C 2018 Published by Elsevier Masson SAS. G Model ARCPED-4632; No. of Pages 6 Please cite this article in press as: Delaplace R, et al. Sleep and disruptive mood dysregulation disorder: A pilot actigraphy study. Archives de Pe ´ diatrie (2018), https://doi.org/10.1016/j.arcped.2018.05.003 Available online at ScienceDirect www.sciencedirect.com https://doi.org/10.1016/j.arcped.2018.05.003 0929-693X/  C 2018 Published by Elsevier Masson SAS.