Background: Post-traumatic stress disorder (PTSD) is the clinical manifestation of traumatic events and is associated with sleep disturbances. Sleep disturbances, if left untreated, may perpetuate or even worsen symptoms of PTSD. Previous studies of other PTSD populations show a higher incidence of sleep impairments and sleep disorders compared to healthy controls (HCs); however, this has never been investigated in trauma-affected refugees diagnosed with PTSD. Objectives: To examine subjective sleep quality, measure sleep architecture, and identify latent sleep disorders in refugees diagnosed with PTSD compared to HCs. Method: This comparative study included 20 trauma-affected refugees diagnosed with PTSD and 20 HC matched on age, sex, and body mass index. All participants completed self-report questionnaires assessing sleep quality, insomnia severity, and disturbing nocturnal behaviour, and all took part in a one-night polysomnography (PSG) assessment. Results: Patients reported significantly poorer subjective sleep quality, sleep latency, sleep duration, and sleep efficiency compared to HCs. Subjective reports on hours spent in bed were not significantly different between patients and HCs. Patients reported significantly higher nightmare frequency and severity compared to HCs. PSG measures showed that patients had significantly reduced sleep efficiency, more awakenings, and longer REM sleep latency, and spent more time awake, whereas there was no significant differences regarding total time in bed, total sleep time, or sleep latency. The prevalence of sleep disorders was equal between groups. Conclusions: The study identified significant impairments in several sleep domains, with a preponderance of disturbed regulation of sleep resulting in awakenings. These results indicate a need for more focus on hyperarousal and nightmares as key elements of disturbed sleep in PTSD. Furthermore, the study identified a discrepancy between subjective and objective measures concerning total sleep time, raising questions regarding the causes of ‘sleep state misperception’. Trial registration:ClinicalTrials.gov identifier: NCT03535636. Trial registration: Sleep Impairments in Refugees Diagnosed with PTSD (PSG-PTSD). URL: https://clinicaltrials.gov/ct2/show/NCT03535636. ClinicalTrials.gov NCT03535636. Date of registration: 24/05/2018.