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So-called confusional arousals -- awakenings without coming fully aware -- were reported in the past year by some 15% of respondents in a population-based survey, with nearly all such episodes associated with mental disorders or drugs known to affect sleep, researchers said.

But 0.9% of the sample reported episodes that could not be attributed to other conditions, and who therefore could qualify for a diagnosis of a primary confusional arousal disorder, according to , of Stanford University in Palo Alto, Calif., and colleagues.

And, contrary to what might have been expected, most episodes were unrelated to sleep-inducers such as zolpidem (Ambien) or eszopiclone (Lunesta), the researchers reported in the Aug. 26 issue of . After adjusting for other risk factors, use of hypnotic drugs was not significantly associated with confusional arousals. In fact, medication use of any kind was present in only a minority of respondents with episodes.

Several psychiatric disorders were associated with episodes, including dysthymic disorder (47.4% of respondents with episodes), bipolar disorders (42.3%), and panic disorder (40.4%). In addition, many types of sleep disorders appeared to raise the risk for the episodes.

Confusional arousals -- also known as sleep drunkenness or severe sleep inertia -- are episodes during which a person awakened from sleep is confused as to time and place and may engage in hostile or violent behaviors, . It often occurs when someone is shaken awake early in the ordinary sleep cycle, but can also present upon normal awakening at the end of a full night's sleep.

, head of the Montefiore Medical Center's Sleep-Wake Disorders Center in Bronx, N.Y., told 番茄社区 that it's a significant problem for some people that deserves investigation and, in some cases, direct treatment.

They occur "when sleep processes are not disengaging" when a person is otherwise coming awake. This most often happens when the patient's brain was deep in sleep, especially the slow-wave type, and some other process -- another person or an internal event -- acts to awaken the patient.

Another specialist, , of the North Shore-LIJ Sleep Disorders Center in New Hyde Park, N.Y., stressed that, in patients whose episodes arise from an underlying condition, "identification of the comorbid disorder is important."

Ohayon and colleagues noted that the syndrome has not received much attention in epidemiological studies. Hence they conducted their own.

Episode Characteristics

With funding from the Arrillaga Foundation, the researchers contacted more than 19,000 adults by telephone, completing interviews with about 16,000. Respondents ranged in age from 18 to 102 and 51% were women. About 20% were currently working evenings or nights; 40% worked during the day.

Among respondents, 2,421 (15.2%) indicated that they had experienced at least one episode during the past year. Of these, just over half said the frequency was at least once weekly, and another 25% reported two to five episodes per month.

For most participants, the episodes had been coming a long time. Some 56% said they began more than 5 years ago and 26% indicated that they had occurred for 1-5 years.

Reported durations of individual episodes averaged less than 5 minutes for about one-third of respondents; another third said they typically lasted 5-15 minutes, and the remainder reported average durations exceeding 15 minutes.

Common features of episodes were as follows:

• Temporospatial disorientation: 57%
• Difficulty speaking or thinking clearly: 34%
• Confused behaviors: 20%
• Hypnagogic or hypnopompic hallucinations: 36%
• Nocturnal wandering: 15%
• No memory of episodes: 9%

Among participants reporting nocturnal wandering, almost half -- 46% -- said they had violent behaviors as part of such episodes.

Thorpy said that confused behaviors range from mistaking a bedside water bottle for a telephone -- thereby dousing themselves when they attempt to answer it -- to urinating in a closet thinking that it's a toilet.

Associations

Ohayon and colleagues asked participants about other sleep problems, neuropsychiatric symptoms, and medications they were taking.

Having other sleep disorders was a clear risk factor for confusional arousal episodes. In adjusted analyses, respondents showing presence of the following disorders had the indicated odds ratios for reporting episodes:

• Excessive sleepiness: OR 1.89 (95% CI 1.68-2.13)
• Circadian rhythm sleep disorder: OR 2.85 (95% CI 2.33-3.48)
• Obstructive sleep apnea: OR 1.79 (95% CI 1.44-2.22)
• Restless legs syndrome: OR 1.61 (95% CI 1.26-2.06)
• Insomnia: OR 1.87 (95% CI 1.55-2.25)
• Hypersomnia: OR 2.40 (95% CI 1.41-4.09)

Overall, participants with a sleep disorder were about three times as likely to report confusional arousals as those without any such conditions.

Several types of psychiatric disorders also showed significant associations with episodes. These included alcohol abuse and dependence, post-traumatic stress, depression, and certain anxiety disorders.

Although the latter included generalized anxiety and panic disorders, some related conditions did not show significant associations after adjusting for other factors. In this category were agoraphobia, social anxiety, and obsessive-compulsive disorders.

With regard to medications, the class most strongly associated with episodes was antidepressants. Selective serotonin and serotonin-norepinephrine reuptake inhibitors, tricyclics, tetracyclics, and other types were each associated with about double the risk of showing confusional arousals.

Hypnotics, anti-anxiety drugs and all other psychotropics lumped together had no association with the episodes in the adjusted analyses. Two-thirds of respondents reporting episodes denied using any psychotropic or sleep medications.

Limitations to the study included reliance on respondents' self-reports for all data. Ohayon and colleagues noted that confusional arousals do not have objective measures, and the presence of amnesia and confusion is likely to lead to under- or misreporting.

They also indicated that confusional arousals are not currently recognized as a diagnosable illness and may not be pathological. On the other hand, they suggested, "including confusional arousals as a sleep disorder in the major classifications would increase awareness among physicians and patients and contribute to its identification, research, and treatment."

Rundo told 番茄社区 that the newest classification of sleep disorders, ICSD-3, which came out after the current study was submitted, does include confusional arousals in its listing of abnormal states.

Thorpy said that confusional arousals may indicate an underlying problem that deserves attention, such as sleep apnea or a seizure disorder.

For the few patients with no apparent cause for the arousals, medications such as benzodiazepines that shorten the slow-wave cycle may be used, he said.

Greenberg said that treatment may be called for "if the bouts occur frequently and are disturbing." He also suggested that, even when they seem benign, "discussion of the nature of the events ... can be reassuring."

, director of Vanderbilt University’s Sleep Disorders Center in Nashville, commented in an email that, while most people may be disoriented momentarily on sudden awakening, the “confusional arousals” designation is not medicalizing a normal behavior.

"Many behaviors, especially in the field of sleep and neurology, exists on a continuum and within the realm of normal. The key is not to say that someone with confusional arousals is having ‘abnormal behavior’ but instead to help them understand what they are experiencing is (a) common, (b) not strange or bizarre, and (c) potentially related to an underlying cause that needs to be addressed (e.g., sleep apnea)," she said.

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