Sleep disturbances are reported by more than 50% of patients with Anorexia Nervosa (AN) and are associated with increased AN severity, psychiatric comorbidities, and poorer quality of life. To date, no pharmacological treatment has been approved or recommended for sleep disorders in children and adolescents with AN. Many drugs are currently prescribed off-label for their sedative side effects, without proven safety or efficacy in this population.

Pediatric prolonged-release melatonin (PedPRM, Slenyto®) is the only melatonin formulation approved by the European Medicines Agency (EMA) for chronic insomnia in children aged 2 to 18 years with neurodevelopmental disorders. Its excellent safety profile, absence of tolerance, and long-acting formulation make it a prime candidate for treating sleep disturbances in children and adolescents with AN.

MELSom-ANOREXIA is a multicenter, randomized, double-blind, placebo-controlled, parallel-group Phase IIIb trial. Its primary objective is to assess the efficacy of PedPRM compared to placebo in improving Total Sleep Time (TST) in children and adolescents aged 6 to 18 years with AN and impaired sleep.

Participants are randomized into two groups: the experimental group receives PedPRM (2 mg or 5 mg depending on response at Day 22) and the control group receives a matching placebo, both administered 0.5 to 1 hour before habitual bedtime for 13 weeks. Sleep is assessed by Sleep Diary and actigraphy. Secondary outcomes include other sleep parameters, AN severity (BMI, EDI-2, EDE-Q), associated symptoms (anxiety, depression, physical activity, executive function, emotionality), and quality of life. Melatonin secretion profiles and specific subgroups (ASD traits, early-onset AN) are also explored.

The study includes a 2-week run-in period (D-14 to D0) for baseline sleep assessment, followed by 13 weeks of treatment, with visits at D0, D22, and D93. A total of 120 participants will be enrolled across 7 French pediatric psychiatry centers over 24 months.

INCLUSION CRITERIA

Participants aged 6 to 18 years, inclusive, with a diagnosis of Anorexia Nervosa (AN) according to DSM-5 criteria Presence of a sleep problem for at least 1 month, defined as ≤ 6 hours of continuous sleep and/or ≥ 0.5 hours sleep latency from lights-off on 3 out of 5 nights, based on participant report (with or without parental assistance according to age), confirmed at D0 by 2-week sleep diary No response to at least 4 weeks of sleep hygiene Negative pregnancy test at baseline, prior to randomization, for female participants of childbearing potential Women of childbearing potential must agree to use a highly effective method of contraception during the study treatment period and for at least 4 weeks after the last dose of study treatment Written informed consent obtained in accordance with the participant's legal status and applicable regulations Affiliation to a social security system or equivalent

EXCLUSION CRITERIA

Known diagnosis of another significant sleep disorder (e.g. moderate to severe sleep apnea) Use of prohibited medication (z-drugs, melatonin agonist, benzodiazepine, phenylpiperazine class, clomethiazole) or melatonin within 2 weeks prior to screening Declared allergy to melatonin, lactose, or any excipient included in the therapeutic units Pregnant or breastfeeding female participants Unresponsiveness to previous prolonged-release melatonin within the 2 years prior to the study Start of cognitive behavioural therapy (CBT) targeting sleep disturbances or mood disorders within 6 weeks before study inclusion Trans-meridian travel (> 2 time zones) within the month before the start of the study Patient under legal protection regimen

Blinding is maintained through the use of placebo therapeutic units identical in appearance and formulation to the PedPRM therapeutic units. Preparation, packaging and labelling of melatonin or placebo units are performed by the Pharmaceutical Expertise and Clinical Research Unit of AP-HM Sponsor to ensure double-blindness. Unblinding may only occur in cases where knowledge of the administered product is strictly necessary for participant management, or in the event of unexpected serious adverse events requiring regulatory reporting.