Cynthia M. Dorsey

Subjective and psychophysiologic insomnia: An examination of sleep tendency and personality

The goal of this study was to compare insomniacs with and without objective verification, on the basis of sleep parameters, personality, and performance. An insomniac complaint group was subclassified as objective insomniac (OI) or subjective insomniac (SI) and compared to a non-complaint group. Groups did not differ on night sleep variables or daytime sleep latency measures; rather, a consistent sleep tendency was revealed for all three groups. The poorer the previous night sleep, the longer the daytime sleep latencies. Groups differed on subjective measures of conscious state during the day. SIs inaccurately estimated sleep/wake state in comparison to objective measures on the MSLT, whereas OIs were accurate in their estimations. Personality scores showed trends that suggested greater neuroticism for SIs and introversion for OIs. Results demonstrated subjective tendencies and related personality types that may help in the understanding of the complaint of insomnia with and without objective findings.

Effects of Passive Body Heating on the Sleep of Older Female Insomniacs

The purpose of this study was to evaluate passive body heating (PBH) as a treatment for insomnia in older adults. Polysomnographic recordings of older adults routinely show an increase in sleep fragmentation and a substantial decrease in slow-wave sleep (SWS) consistent with complaints of “lighter” more disturbed sleep. An increase in body temperature in young adults early in the evening by way of PBH has been shown to produce an increase in SWS in the early part of the sleep period. In a crossover design, nine female insomniacs (aged 60–72 yr) participated in two consecutive nights of PBH, involving hot (40–40.5°C) and luke-warm (37.5–38.5°C) baths 1.5 hours before bedtime. Significant improvement in sleep continuity and a trend toward an increase in SWS occurred after hot baths. Results of subjective measures showed that subjects experienced significantly “deeper” and more restful sleep after hot baths. In addition, hot baths resulted in a significant delay of temperature nadir in comparison to baseline nights.

Response inhibition and psychomotor speed during methadone maintenance: impact of treatment duration, dose, and sleep deprivation

BACKGROUND In opiate-dependent individuals, abstinence results in deficits in cognitive functioning, which may be exacerbated by medication-associated sleep disruption. METHOD To assess cognitive function and the influence of sleep deprivation (SD), 14 healthy control (HC) and 22 methadone maintained (MM) participants completed the continuous performance task (CPT) after a baseline night, a night of total SD, and two recovery sleep nights. The digit symbol substitution task (DSST) was administered at bedtime and in the morning. Secondary analyses separated MM participants into short- (< 12 months; n=8) and long-term (≥ 12 months; n=14) treatment duration groups, and into low- (< 80 mg; n=9) and high-dose (≥ 80 mg; n=13) groups. RESULTS Linear mixed model ANOVAs revealed that there was no effect of SD. Across all days MM participants had more errors of omission, fewer correct responses, and slower reaction times (RTs) on the CPT, and fewer accurate substitutions on the evening and morning DSST. Short-term MM participants exhibited slower RTs on the CPT, and fewer correct substitutions on the evening DSST compared to long-term MM participants. Low-dose MM participants had slower RTs on the CPT than HCs and high-dose MM participants. CONCLUSION These data demonstrate that methadone-maintained individuals exhibit poorer performance on tasks of psychomotor speed and selective attention/impulsivity, but with longer-term treatment, performance appears to return toward control levels. Furthermore, while one day of SD was enough to alter subjective reports of sleep quality, cognitive function may be more resilient.

Effects of sleep deprivation on sleep homeostasis and restoration during methadone-maintenance: A [31]P MRS brain imaging study

Insomnia afflicts many individuals, but particularly those in chronic methadone treatment. Studies examining sleep deprivation (SD) have begun to identify sleep restoration processes involving brain bioenergetics. The technique ([31])P magnetic resonance spectroscopy (MRS) can measure brain changes in the high-energy phosphates: alpha-, beta-, and gamma-nucleoside triphosphate (NTP). In the present study, 21 methadone-maintained (MM) and 16 control participants underwent baseline (BL), SD (40 wakeful hours), recovery1 (RE1), and recovery2 (RE2) study nights. Polysomnographic sleep was recorded each night and ([31])P MRS brain scanning conducted each morning using a 4T MR scanner (dual-tuned proton/phosphorus head-coil). Interestingly, increases in total sleep time (TST) and sleep efficiency index (SEI) commonly associated with RE sleep were not apparent in MM participants. Analysis of methadone treatment duration revealed that the lack of RE sleep increases in TST and SEI was primarily exhibited by short-term MM participants (methadone <12 months), while RE sleep in long-term MM (methadone >12 months) participants was more comparable to control participants. Slow wave sleep increased during RE1, but there was no difference between MM and control participants. Spectral power analysis revealed that compared to control participants; MM participants had greater delta, theta, and alpha spectral power during BL and RE sleep. ([31])P MRS revealed that elevations in brain beta-NTP (a direct measure of ATP) following RE sleep were greater in MM compared to control participants. Results suggest that differences in sleep and brain chemistry during RE in MM participants may be reflective of a disruption in homeostatic sleep function.

An electromyographic marker for neuroleptic-induced akathisia : Preliminary measures of sensitivity and specificity

Previous polysomnographic (PSG) investigations have reported a rhythmic electromyographic (EMG) pattern (0.5-3.0 cps) of leg movement activity in a subset of patients with neuroleptic-induced akathisia (NIA). It has been suggested that this EMG pattern may represent a pathophysiological correlate of NIA and thus have clinical utility as an objective marker for this condition. We present preliminary measures of sensitivity and specificity for this EMG pattern as a diagnostic marker for NIA for 26 neuroleptic-treated patients. The EMG marker yielded a diagnostic sensitivity of 68.9% and a specificity of 70.0%, falling just short of statistical significance (Fishers exact test p = 0.06). Quantitative analysis of the EMG pattern revealed a significant positive correlation between the percentage of time the NIA marker occurred during wakefulness and corresponding chlorpromazine equivalent levels. Clinical demographic findings for true-positive, false-positive, true-negative, and false-negative groups are discussed. Overall findings suggest that this particular pattern of EMG marker activity observed in neuroleptic-treated patients during PSG and EMG studies is valuable in facilitating the diagnosis and monitoring treatment.

Gray matter-specific changes in brain bioenergetics after acute sleep deprivation: a 31P magnetic resonance spectroscopy study at 4 Tesla.

STUDY OBJECTIVES A principal function of sleep may be restoration of brain energy metabolism caused by the energetic demands of wakefulness. Because energetic demands in the brain are greater in gray than white matter, this study used linear mixed-effects models to examine tissue-type specific changes in high-energy phosphates derived using 31P magnetic resonance spectroscopy (MRS) after sleep deprivation and recovery sleep. DESIGN Experimental laboratory study. SETTING Outpatient neuroimaging center at a private psychiatric hospital. PARTICIPANTS A total of 32 MRS scans performed in eight healthy individuals (mean age 35 y; range 23-51 y). INTERVENTIONS Phosphocreatine (PCr) and β-nucleoside triphosphate (NTP) were measured using 31P MRS three dimensional-chemical shift imaging at high field (4 Tesla) after a baseline night of sleep, acute sleep deprivation (SD), and 2 nights of recovery sleep. Novel linear mixed-effects models were constructed using spectral and tissue segmentation data to examine changes in bioenergetics in gray and white matter. MEASUREMENTS AND RESULTS PCr increased in gray matter after 2 nights of recovery sleep relative to SD with no significant changes in white matter. Exploratory analyses also demonstrated that increases in PCr were associated with increases in electroencephalographic slow wave activity during recovery sleep. No significant changes in β-NTP were observed. CONCLUSIONS These results demonstrate that sleep deprivation and subsequent recovery-induced changes in high-energy phosphates primarily occur in gray matter, and increases in PCr after recovery sleep may be related to sleep homeostasis.

Effects of Sleep Deprivation on Brain Bioenergetics, Sleep, and Cognitive Performance in Cocaine-Dependent Individuals

In cocaine-dependent individuals, sleep is disturbed during cocaine use and abstinence, highlighting the importance of examining the behavioral and homeostatic response to acute sleep loss in these individuals. The current study was designed to identify a differential effect of sleep deprivation on brain bioenergetics, cognitive performance, and sleep between cocaine-dependent and healthy control participants. 14 healthy control and 8 cocaine-dependent participants experienced consecutive nights of baseline, total sleep deprivation, and recovery sleep in the research laboratory. Participants underwent [31]P magnetic resonance spectroscopy (MRS) brain imaging, polysomnography, Continuous Performance Task, and Digit Symbol Substitution Task. Following recovery sleep, [31]P MRS scans revealed that cocaine-dependent participants exhibited elevated global brain β-NTP (direct measure of adenosine triphosphate), α-NTP, and total NTP levels compared to those of healthy controls. Cocaine-dependent participants performed worse on the Continuous Performance Task and Digit Symbol Substitution Task at baseline compared to healthy control participants, but sleep deprivation did not worsen cognitive performance in either group. Enhancements of brain ATP levels in cocaine dependent participants following recovery sleep may reflect a greater impact of sleep deprivation on sleep homeostasis, which may highlight the importance of monitoring sleep during abstinence and the potential influence of sleep loss in drug relapse.