Sleep state misperception
|Sleep state misperception|
|Classification and external resources|
|ICD-9||307.42, 307.49, 780.52|
Sleep state misperception (SSM) is a term in the International Classification of Sleep Disorders (ICSD) most commonly used for people who mistakenly perceive their sleep as wakefulness, though it has been proposed that it be applied to those who severely overestimate their sleep time as well ("positive" sleep state misperception). While most sleepers with this condition will report not having slept in the previous night at all or having slept very little, clinical recordings demonstrate normal sleep patterns. Moreover, patients are otherwise generally in good health, and any ills—such as depression—appear to be more associated with fear of negative consequences of insomnia ("insomnia phobia") than from any actual loss of sleep.
Sleep state misperception was adopted by the ICSD to replace two previous diagnostic terminologies: "subjective insomnia complaint without objective findings" and "subjective sleepiness complaint without objective findings."
Other synonyms of the term include: paradoxical insomnia, pseudo-insomnia, subjective insomnia, subjective sleepiness, and sleep hypochondriasis.
Sleep state misperception is classified as an intrinsic dyssomnia. While SSM is regarded a sub-type of insomnia, it is also established as a separate sleep-condition, with distinct pathophysiology. Nonetheless, the value of distinguishing this type of insomnia from other types is debatable due to the relatively low frequency of SSM being reported.
Sleep state misperception can also be further broken down into several types, by patients who—
- report short sleep (subjective insomnia complaint without objective findings)
- or no sleep at all (subjective total insomnia)
- report excessive daytime sleepiness (subjective sleepiness complaint without objective findings)
- report sleeping too much (subjective hypersomnia without objective findings)
Symptoms and diagnosis
This sleep disorder frequently applies when patients report not feeling tired despite their subjective perception of not having slept. Alternatively, patients may report excessive daytime sleepiness or insomnia, while lacking factors often associated with those symptoms such as sleep apnea syndrome or another sleep disorder. Generally, they may describe experiencing several years of no sleep, short sleep, or non-restorative sleep. Otherwise, patients appear healthy, both psychiatrically and medically. (That this condition is often asymptomatic could explain why it is relatively unreported.)
However, upon clinical observation, it is found that patients may severely overestimate the time they took to fall asleep—often reporting having slept half the amount of time indicated by polysomnogram or electroencephalography (EEG), which may record normal sleep. Thus, it becomes evident that the perception of poor sleep is primarily illusionary. Moreover, reports of daytime sleepiness may be a result of the nocebo response—the reverse of the placebo effect—due to patient expectations of adverse effects from their subjective perception of poor sleep.
Due to the subjective nature of this complaint, which depends on patient self-reporting of sleep, it is not currently measurable by objective means. One woman affected by SSM began contemplating suicide “because no one can figure out what is wrong with me” after being repeatedly dismissed as normal by various doctors and receiving insomnia treatments that did not work from others.
A recent study published in the journal Psychosomatic Medicine has shown that sleep misperception (i.e., underestimation of sleep duration) is prevalent among chronic insomniacs who sleep objectively more than 6 hours in the sleep lab. The psychological profile of these chronic insomniacs with objective normal sleep duration is characterized by depressive, anxious-ruminative traits and poor coping resources. Thus, it appears that not all chronic insomniacs underestimate their sleep duration, and that sleep misperception is a clinical characteristic of chronic insomniacs with objective normal sleep duration. Furthermore, rumination and poor coping resources may play a significant role in sleep misperception.
Behavioral treatment can be effective in some cases. Sedative hypnotics may also help relieve the symptoms. Additionally, education about normal patterns of the sleep-wake cycle may alleviate anxiety in some patients. For patients with severe depression resulting from the fear of having insomnia, electroconvulsive therapy appears to be a safe and effective treatment.
The condition may worsen as a result of persistent attempts to treat the symptoms through conventional methods of dealing with insomnia. The prescription of hypnotics or stimulants may lead to drug dependency as a complication.
Nonetheless, chronic SSM may increase risk for depression, anxiety, and substance abuse. It has also been noted that patients with this condition may sometimes opt to take medications over other treatments "for the wrong reasons (e.g. because of euphoriant properties)."
Distinction from "true" insomnia
Objective insomnia, unlike SSM, can be confirmed empirically through clinical testing, such as by polysomnogram. In other words, those who experience SSM may believe that they have not slept for extended periods of time, when they in fact do sleep but without perceiving so.
Moreover, cases of objective total insomnia are extremely rare. The few that have been recorded have predominantly been ascribed to a rare incurable genetic disorder called fatal familial insomnia, which patients rarely survive for more than 26 months after the onset of illness—often much less. While rarer cases of objective total insomnia lasting for decades have been reported, such as with the American Al Herpin and the Vietnamese Thai Ngoc, they have not been studied extensively in a clinical setting.
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