Use of Suvorexant for Sleep Regulation in an Adolescent with Early-Onset Bipolar Disorder

To the Editor:

A cardinal symptom of adolescent bipolar mania is decreased need to sleep. Treating insomnia and achieving regular cycles of sleep/wake time are important in the treatment of adolescent bipolar disorder. Up to 70% of bipolar patients report insomnia, and this is associated with risk of relapse, affective dysregulation, interepisode functional impairment, and suicide attempts (Harvey et al., 2015). Psychological interventions for bipolar insomnia include interpersonal and social rhythm therapy, family therapy, cognitive behavioral therapy, and psychoeducation (Harvey et al., 2015). Pharmacological treatments include over-the-counter formulations, sedative antidepressants, benzodiazepines, nonbenzodiazepines hypnotics, and melatonin receptor agonists. In adolescents, these medications are used to treat insomnia only as off-label. Side effects such as residual daytime sleepiness, tolerance, dependence, and rebound insomnia may occur.

In this study, we present a case of an adolescent with bipolar I disorder who successfully regulated his sleep using suvorexant after failure with multiple other agents.

A 16-year-old boy (body mass index = 23.18 kg/m², z = 0.52) with bipolar I disorder, and a multigenerational familial risk for bipolar illness, complained of decreased need for sleep despite successful mood stabilization with valproate 1250 mg/day (level 55 μg/mL) and lurasidone 140 mg/day. He experienced chronic sleep difficulties, usually sleeping 3–4 hours per night with both initial insomnia and early morning awakenings, related to his affective symptoms rather than to a primary sleep disorder. Insomnia was associated with irritability, low frustration tolerance, and aggression both at home and at school. Previous medication trials, including melatonin 10 mg, trazodone 50 mg, quetiapine 800 mg, and clonazepam 0.5–1 mg, were either poorly tolerated or ineffective. After informed consent, a low-dose (10 mg) trial of suvorexant successfully improved his insomnia. Sleep duration improved to 6–7 hours per night (by mother report), sleep quality improved, and the patient reported more refreshing sleep. Mother notes that with his better-quality sleep, irritability during the day improved greatly, he is less aggressive at home and school, and his academic performance is slowly improving. During 7 months of use, suvorexant has been well tolerated without report of daytime sedation or other adverse effects. The effective dose has not changed since there is no evidence of tolerance or waning effect over time.

Suvorexant is a reversible dual orexin receptor antagonist approved for adult insomnia by the Food and Drug Administration in 2014. Suvorexant reversibly antagonizes orexin-A and B receptors inhibiting the arousal system. It is indicated for sleep onset and sleep maintenance in adults at a dose range of 5–20 mg. Side effects are dose dependent and include daytime somnolence, headaches, dizziness, and abnormal dreams. Higher doses have been associated with motor impairment and unconscious night-time activity (Kay-Stacey and Attarian, 2016).

To the best of our knowledge, there is only one small open-label study of suvorexant use in adolescents with insomnia. This study found significant improvement in subjective sleep quality in those adolescents who took suvorexant 20 mg/day and completed the study (17/30 patients, 56.7%) (Kawabe et al., 2017). Our case suggests that suvorexant might be well tolerated and effective in the treatment of persistent bipolar insomnia. It is important to further investigate the use of suvorexant as a possibly effective option in sleep cycle regulation in adolescent bipolar disorder.