Impact of Hyperarousal on Simple and Complex Cognitive Task Performance Among Insomnia Sufferers
Condition: Insomnia; Primary Insomnia; Chronic Insomnia
MeSH terms: Sleep Initiation and Maintenance Disorders
Study type: Observational

Summary: 
      The purpose of this study is to learn more about people with insomnia disorder and cognitive
      impairment. Cognitive impairment is difficulty with mental abilities such as thinking,
      knowing and remembering.
    

Detailed description: 
      Primary insomnia (PI) sufferers typically complain of such daytime impairments as reduced
      attention, concentration, memory and global mental acuity. Moreover, epidemiological studies
      have shown PI contributes to reduced productivity, work and traffic accidents, and serious
      falls among the elderly. Despite such findings, laboratory-based efforts to corroborate the
      cognitive complaints of PI sufferers have produced mixed results. Indeed, many studies
      comparing PI sufferers with non-complaining normal sleepers across a range of
      neuropsychological tests have failed to show any relative deficits among the PI group. Such
      findings, in turn, has led to the impression that PI patients cognitive complaints may be
      over-stated and result from their attentional bias toward minor cognitive errors,
      dysfunctional beliefs about the impact of insomnia on functioning or excessive self focus
      rather than to any measurable daytime impairment.

      However, many previous such studies were underpowered due to small sample sizes and employed
      neuropsychological tests designed for detecting impairment resulting from brain
      disease/damage rather than the more subtle albeit significant impairments of which PI
      patients complain. In recent research, we and others have shown that PI sufferers do, indeed,
      show greater deficits (slower and more variable reaction times) particularly on complex
      switching attention tasks. Moreover, there is some preliminary evidence that the subgroup of
      PI sufferers with elevated levels of physiological hyperarousal are most prone to suffer from
      neuro-cognitive performance deficits than are matched groups of PI sufferers who are not
      physiologically hyperaroused and normally alert individuals without insomnia. For example,
      Fernandez-Mendoza recently showed that PI sufferers with a hyperarousal pattern suggested by
      their objective short sleep duration on serial polysomnograms (PSG) performed more poorly on
      a complex switching attention task than did both normal sleepers and PI sufferers with normal
      objective sleep durations.

      In our efforts to follow up on this latter work, we recently examined the error rates of
      alert and sleepy PI sufferers and normal sleepers across a series of simple and complex
      reaction time tasks. We employed age and gender matched samples of PI (N=89) sufferers and
      normal sleepers-NS (N=95). Participants underwent three nights of PSG followed by daytime
      testing with a four-trial Multiple Sleep Latency Test-MSLT. The PI and NS groups were each
      subdivided into "alert" (e.g., MSLT mean onset latency > 8 minutes) and "sleepy" (e.g., MSLT
      mean onset latency < 8 minutes) subgroups to allow for testing the main and interaction
      effects of participant type and level of alertness. "Alert" participants had longer MSLT
      latencies than "sleepy" participants (12.7 vs. 5.4 minutes). PI sufferers had fewer correct
      responses on performance testing than did NS. However, as shown by the adjacent, figure we
      found a significant group x alertness interaction (p = .0013) with greater error rates
      occurring among alert (hyperaroused) PI sufferers (Mean=4.5±3.6 errors per trial) than among
      alert NS (Mean=2.6±1.9 errors per trial). This was particularly true for the more complex
      switching attention task.

      Our work along with that of Fernandez-Mendoza serve to confirm that PI sufferers have
      measureable objective neuro-cognitive deficits and provide some preliminary suggestion for
      the types of testing approaches that should be used to detect them. The identification of
      tests sensitive to PI sufferers' cognitive deficits are particularly relevant for testing the
      effects of current and future insomnia therapies on patients' objective daytime functioning.
      Measures of daytime dysfunction can and should serve as endpoints for assessing benefits and
      detriments of insomnia therapies. In addition, our recent work suggests that subgroups of PI
      sufferers may differ in their daytime deficits, with those showing physiological hyperarousal
      being most prone to make errors. This finding suggests that different types or doses of
      treatment may be needed to reverse the daytime impairments of the hyperaroused and
      non-aroused PI patients. However, our line of research would benefit by replication and
      extension findings to (1) further confirm the detrimental effects of physiological
      hyperarousal on PI sufferer's neuro-cognitive functioning; and (2) identify a broader range
      of tests that can be used for assessing diurnal cognitive impairments in both physiologically
      hyperaroused and lesser aroused PI groups. The current project will address these aims.
    

Intervention name(s): Multiple Sleep Latency Test (MSLT)
Intervention type(s): Behavioral
Intervention description(s): The daytime protocol will include a 4-trial Multiple Sleep Latency Test (MSLT) along with 4-trials of a computer -administered battery of reaction time tasks. The assessment protocol will start two to three hours after participants' respective morning rising times and will begin with a battery of the neuro-cognitive testing followed by an MSLT nap. Per standard MSLT procedures, the daytime testing will be scheduled so the four performance testing and sleepiness assessment trials occur two hours apart. All daytime testing will be conducted under the supervision of trained laboratory technologists.
Observational model: Cohort
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        This study will use a matched-groups cross-sectional experimental design. Age and gender
        matched groups of hyperaroused PI sufferers and non-complaining normal sleepers (NS) will
        be recruited and enrolled. A comprehensive screening process that includes structured sleep
        and psychiatric interviews, screening questionnaires, medical exam, and diagnostic PSG will
        be used to determine eligible subjects.
      
Keywords: insomnia; primary insomnia; chronic insomnia