According to a research group led by Karin Trimmel and Stefan Seidel from MedUni Vienna’s Department of Neurology (Outpatient Clinic for Sleep Disorders and Sleep-Related Disorders), people with sleep disorders commonly have a misperception about their actual sleep behavior. The researchers analyzed polysomnography results to identify the types of sleep disorders that are associated with a discrepancy between self-reported and objective sleep parameters and whether there are influencing factors. 
The main finding: irrespective of age, gender or screening setting, insomnia patients are most likely to underestimate how long they sleep. The study has been published in the Journal of Clinical Sleep Medicine. Patients’ misperceptions about the actual time that they sleep is a well-known phenomenon in sleep research.
Their own impression of their sleep behavior is often quite different from that demonstrated by clinical measurements. Nonetheless, until now there had been no scientific comparison between patients’ actual total sleep time and their self-reported sleep time that also analyzed associated factors.
Researchers discovered a discrepancy between self-reported perception and objective readings in all sleep disorders, although it was largest in the case of insomnia, irrespective of age, sex or whether the monitored night was spent in the sleep lab or at home. Insomnia patients overestimate their sleep latency, that is to say the time it takes them to fall asleep, and significantly underestimate the amount of total sleep time.
A constantly elevated level of background stress (hyperarousal) could be a factor in this, since this would result in disrupted sleep architecture (increased number of microarousals), as well as the fact that insomnia is often associated with psychiatric comorbidities. In contrast to insomnia patients, patients with other sleep disorders tended to underestimate their sleep latency and overestimate their total sleep time.
The study corroborates the clinical observation that sleep misperception occurs in all forms of sleep disorder but is most prevalent in insomnia. The treatment of choice in this instance is cognitive behavioral therapy. Karin Trimmel explains: “By incorporating this misperception into behavioral therapy, we can significantly improve treatment outcomes, so that polysomnography is highly recommended for patients with treatment-resistant insomnia.”