Background: High prevalence of sleep disturbance, which is associated with poor mental health, has been observed among non-treatment seeking refugees. However, no longitudinal research has investigated the chronicity of untreated sleep disturbance and its impact on refugees' mental health. Objective: This longitudinal study investigated associations between mental health (posttraumatic stress disorder, anxiety, depression), sleep symptoms (insomnia severity, pre-sleep arousal), and factors predicting mental health, over a 12-month period. Method: Syrian refugees (N = 69) from a cross-sectional study (Time 1) participated in the current 12-month (Time 2) follow-up study. Participants completed a series of questionnaires examining sleep, trauma exposure, post-migration living difficulties, and mental health at both time points. Results: When compared to Time 1, participants showed a significant increase in postmigration stress at Time 2. However, there was an improvement in their mental health and levels of sleep disturbance. Half of the participants met criteria for moderate (36%) or severe sleep disturbance (15%) at Time 2. Forty-two per cent of the participants had moderate to severe sleep disturbance at both Time 1 and Time 2. When predicting mental health at 12month follow-up, only pre-sleep arousal at Time 1 uniquely predicted mental health at Time 2. Mediation analysis indicated that change in pre-sleep arousal (from Time 1 to Time 2) significantly mediated the relationship between change in post-migration stress and change in mental health symptoms. Conclusions: This study demonstrated that sleep symptoms have an indirect and long-term impact on mental health among refugees. Understanding modifiable factors, such as sleep, mediating the relationship between trauma exposure and PTSD symptoms is important, as such factors can be targeted in psychological interventions for refugees. Investigación Longitudinal de la Relación entre la Exposición al Trauma, el Estrés Post-migratorio, las Alteraciones del Sueño, y la Salud Mental en Refugiados Sirios Antecedentes: Se ha observado en refugiados que no están en búsqueda de tratamiento una alta prevalencia de alteraciones del sueño, que se asocia con una salud mental pobre. Sin embargo, no existen estudios longitudinales que hayan investigado la cronicidad de las alteraciones del sueño no tratadas y su impacto en la salud mental de los refugiados. Objetivo: Este estudio longitudinal investigó las asociaciones entre salud mental (trastorno de estrés postraumático, ansiedad, depresión), síntomas del sueño (severidad del insomnio, activación previa al sueño), y factores predictores de salud mental, a lo largo de un periodo de 12 meses. Método: Refugiados sirios (N=69) de un estudio transversal (Momento 1) participó en el siguiente seguimiento a los 12 meses (Momento 2). Los participantes completaron una serie de cuestionarios examinando el sueño, la exposición al trauma, las dificultades vitales luego de la migración y la salud mental en ambos momentos de medición. Resu...