![]() ![]() Little is known about the mechanisms underlying sleep misperception. Differential diagnoses include malingering and, particularly when the mismatch between subjective and objective measurements of sleep is less marked than in our patient, other types of primary insomnia such as psychophysiological or idiopathic insomnia. Their results supported the initial clinical impression of sleep state misperception. Because of the extreme sleep loss reported by the patient, the absence of daytime impairment and of symptoms suggestive of another type of insomnia, polysomnography and actimetry were recommended. In our patient, all ICSD-2 diagnostic criteria were present, although we were not able to convince the patient to keep a sleep diary. 2 In the absence of adequate general population studies and given the variability in clinic-based study results, the prevalence is difficult to ascertain 2 but it is probably low, paradoxical insomnia affecting less than 5% of insomniacs. Overestimation of sleep latency and wake after sleep onset and underestimation of total sleep time are common in most insomniacs, but in patients with paradoxical insomnia, the discrepancy between subjective and objective sleep is far greater. 1 Paradoxical insomnia is characterized by a discrepancy between subjective sleep time and objective sleep evaluated by polysomnography (PSG) or actimetry, constant rumination and/or awareness of external stimuli during the night and a level of daytime impairment inconsistent with the reported sleep deprivation. "Paradoxical insomnia" is a primary insomnia subtype introduced in the revised International Classification of Sleep Disorders in 2005 to replace the former "Sleep State Misperception" category. Additionally, actigram consistently shows nocturnal sleep periods of 8 hours or longer (highlighted in red). PSG analysis shows an objective total sleep time of 8 hours, while the patient reported an estimated sleep time that night of less than one hour. The patient suffers from paradoxical insomnia: the discrepancy between estimated sleep time and objective sleep time calculated on PSG (supported, in this case, by the results of actimetry) and the lack of daytime consequences of the drastic sleep loss reported by the patient are the essential features of this insomnia subtype. Home polysomnography was performed on the night of April 13 (dotted arrow). The second cycle on a line is the same as the first cycle on the following line. Recordings were made at one minute periods. Image 2: Patient’s double plot actigram recorded during a one-week vacation. EVEIL = wakefulness SP = Rapid Eye Movement sleep, 1 = stage N1 2 = stage N2 3 = stage N3. Image 1: Patient’s PSG hypnogram for the night of April 13 (dotted line on Image 2). The actimetry results are shown in Image 2. The PSG hypnogram is shown in Image 1 and sleep parameters are presented in the table. The PSG was recorded on the first night of the week, when the patient reported that she had slept less than one hour during the night. This testing was obtained during a week of scheduled vacation when she stated that she had tried to sleep longer at night, by later rising and by napping during the afternoon, with no success. Thus, only home polysomnography (PSG) and actimetry were obtained. The patient was reluctant to keep a sleep log, stating that "she never slept at all anyway". Significant medical history included severe depression two years prior to the initial sleep assessment, with successful treatment with antidepressant medication and psychotherapy, which had been discontinued after a year. Caffeine intake was limited to one cup of coffee in the morning. ![]() In spite of this profound insomnia, the patient reported mild fatigue but no significant daytime sleepiness (Epworth sleepiness score = 9/24) and no cognitive dysfunction. She had taken various hypnotic drugs over the last two years and eventually stopped because of lack of efficacy. The patient’s thoughts revolved around the past and upcoming work day, her family life as well as current events in the news. ![]() ![]() She reported constant mental activity during the night. She stated that she hardly ever slept, at least never more than 3 hours a night. A 46 year old woman presented to the Sleep Clinic with a complaint of severe insomnia dating back at least ten years. ![]()
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