Behavioral,subjective, and electroencephalographic indices of sleep onset latency and sleep duration

Electrographic (EEG, EOG, EMG) indices have been used for some decades in the definition of the stages of sleep and more recently in the diagnosis of sleep-related disorders, e.g., insomnia, despite the lack of detailed information concerning the precise relationship between such electrographic indices and behavioral and subjective criteria of sleep. Evaluation of the relationship between EEG, behavioral, and self-report measures of sleep onset latency and sleep duration was conducted using 17 young normal sleepers. The behavioral measure was provided by an apparatus which records subjects' button-press responses to an auditory stimulus presented at various interstimulus intervals (2, 5, and random 1, 2, 5, 7, and 10 min). The behavioral and stage 2 EEG estimates of sleep onset latency (SOL) and sleep duration (SD) were almost identical. The stage 1 EEG provided the shortest estimate of SOL; the self-report measure, the longest. The SD measures were in reverse order. There were no significant differences among the three interstimulus interval conditions (2, 5, and random min). Average response rates to the 50-dB chime were 100% during wakefulness, 81% during EEG stage 1, and 8% during EEG stage 2. Almost all stage 2 responding occurred during the first 5 min of each stage 2 period. The validity of electrographic indices as sleep criteria and the implications of the findings for the formulation of an adequate definition of sleep and its clinical measurement are discussed.     

Anxiety sensitivity and daily cigarette smoking in relation to sleep disturbances in treatment-seeking smokers

ABSTRACT

Although the association between anxiety and sleep disturbance is well-documented, the underlying mechanisms are less clear. Anxiety sensitivity (AS), the fear of physiological arousal and bodily sensations, is a risk factor for anxiety and poor sleep. Smoking also contributes to poor sleep and may compound the effects of AS on sleep quality. This study evaluated the main and interactive effects of AS and cigarettes/day on sleep quality among smokers. Participants (n = 190) were adult treatment-seeking daily smokers who completed a baseline assessment as part of a larger smoking cessation trial. Sleep quality was self-reported. Results indicated that AS was significantly correlated with greater disturbance in sleep duration, subjective sleep quality, sleep onset latency, sleep disturbance, daytime dysfunction, and sleep medication use. There was a significant interaction between AS and cigarettes/day in terms of sleep onset latency, but not other sleep quality indices. AS was associated with significantly longer sleep onset latency minutes among heavier smokers, but not lighter smokers. Specifically, the association between AS and sleep onset latency was significant for those who smoked ≥ 33 cigarettes/day. AS is a psychological factor that may contribute to poor sleep quality, especially in heavy smokers, and thus may be a promising intervention target.     

A FADED BEDTIME WITH RESPONSE COST PROTOCOL FOR TREATMENT OF MULTIPLE SLEEP PROBLEMS IN CHILDREN

The sleep-wake cycles of 4 developmentally delayed individuals with longstanding severe sleep disturbances were regulated using a faded bedtime procedure with response cost. Bedtimes were systematically delayed for each individual, thus increasing the probability of short latency to sleep onset. The response cost component, consisting of removing the individual from bed for 1 hour, was implemented when an individual did not experience short latency to sleep onset. A fading procedure was then applied successfully to advance the bedtimes and to gradually increase durations of sleep. Specifically, all 4 individuals had decreased amounts of nighttime sleep that increased following treatment. Two of the 4 individuals showed excessive daytime sleep that decreased following treatment. Three of the 4 individuals experienced decreases in night wakings following treatment. Both environmental and biological manipulations of the sleep-wake cycle are hypothesized as mechanisms of treatment. The relative advantages of this procedure over other procedures for the treatment of pediatric sleep disorders are discussed, as are directions for future research.     

Relationships Among Sleep Disturbance,Reward System Functioning,Anhedonia, and Depressive Symptoms

Recent models propose reward system dysfunction as a key mediator of the relationship between sleep and depression and anhedonia. This study explored interrelationships among sleep disturbance, depressive symptoms, anhedonia, and reward responsiveness. Two-hundred and sixty undergraduate students completed questionnaires and a daily diary paradigm assessing sleep, reward responsiveness, depression, anhedonia, and positive affect over 1 week. Baseline sleep disturbance was associated with depressive symptoms, anhedonia, and reward responsiveness. Daily diary sleep parameters showed differential associations with anticipatory versus consummatory reward responsiveness and positive affect. Poorer sleep quality, shorter sleep duration, and longer awakening after sleep onset predicted blunted anticipatory and consummatory reward responsiveness, while increased sleep onset latency and lower sleep efficiency predicted only decreased consummatory reward responsiveness. All sleep indices, except sleep onset latency, were associated with positive affect. Findings demonstrate unique associations between disparate sleep disturbance and reward responsiveness elements, highlighting new treatment mechanisms for anhedonia and depression.     

Comparison of Motionlogger Watch and Actiwatch actigraphs to polysomnography for sleep/wake estimation in healthy young adults

Sleep/wake identification and sleep parameter estimates from Motionlogger Watch and Actiwatch-64 actigraphs were compared to polysomnography (PSG). Following one night of baseline sleep, 29 volunteers remained awake for 36 h, followed by 11 h of recovery sleep in the laboratory. Two sets of analyses were performed: (1) epoch-by-epoch agreement and discriminability index (d') calculations, and (2) sleep parameter concordance with repeated measures ANOVAs. Sensitivity (sleep identification), specificity (wake detection), and overall agreement with PSG, as well as d', were higher for the Motionlogger than for Actiwatch. Relative to PSG, the Actiwatch-estimated total sleep time and sleep efficiency were underestimated and the number of awakenings was overestimated for baseline and recovery; sleep latency was underestimated on the baseline night. On the other hand, the Motionlogger-estimated total sleep time and sleep efficiency estimates were underestimated, and the sleep latency was overestimated on recovery, versus PSG. Despite these misestimations, it was concluded that the Motionlogger provided nominally better agreement with PSG, and that actigraphy generally constitutes a reasonably reliable tool for producing objective measurements of sleep/wake, but that users should remain mindful of its limitations.     

Subjective Sleep Disturbances in Sexual Assault Survivors: Associations With Trauma and Posttraumatic Stress Disorder Symptom Severity

Prior work implicates sleep disturbance in the development and maintenance of posttraumatic stress disorder (PTSD). However, the majority of this literature has focused on combat veteran men, and limited work has examined links between sleep disturbance and PTSD symptoms in sexual assault survivors. This is a notable gap in the literature, as sexual trauma is disproportionately likely to result in PTSD and is more common in women. We sought to examine the relations between subjective sleep disturbance, sexual assault severity, and PTSD symptoms in a sample of sexual assault survivors with PTSD (PTSD+), without PTSD (PTSD-), and healthy controls. The sample (N = 60) completed the Insomnia Severity Index and prospectively monitored their sleep for 1 week using the Consensus Sleep Diary. The sexual assault survivors also completed the Sexual Experiences Survey and PTSD Checklist-5. Results of group comparisons found that the PTSD+ group reported significantly higher insomnia symptoms, longer sleep onset latency, more nocturnal awakenings, and lower sleep quality compared to the healthy control group and higher insomnia symptoms compared to the PTSD- group. Results of regression analyses in the sexual assault survivors found that insomnia symptoms and number of nocturnal awakenings were significantly associated with higher PTSD symptoms, and sexual assault severity was significantly associated with higher insomnia symptoms, longer sleep onset latency, and lower sleep quality. These findings highlight specific features of sleep disturbance that are linked to trauma and PTSD symptom severity among sexual assault survivors.     

A within-subject analysis of stimulus control therapy with severe sleep-onset insomnia.

Stimulus control, a behavioral technique designed to reduce sleep difficulties, has been demonstrated to be effective when compared with control procedures. These comparisons, mainly involving between-subjects analyses, have neglected the contribution of the stimulus control procedure to the production of clinically significant amelioration of sleep dysfunction. In contrast, the present within-subjects experiment was conducted to assess the capability of stimulus control to produce clinically relevant reductions in multiple measures of sleep disturbance. A comparison with the credible placebo procedure indicated that the stimulus control techniques reduced subjects' sleep onset latency to a mean latency below 30 min per week. Additionally, sedative-hypnotic usage was greatly reduced.     

Anticipatory attention during the sleep onset period

To examine whether anticipatory attention or expectancy is a cognitive process that is automatic or requires conscious control, we employed a paired-stimulus event-related potential (ERP) paradigm during the transition to sleep. The slow negative ERP wave observed between two successive stimuli, the Contingent Negative Variation (CNV), reflects attention and expectancy to the second stimulus. Thirteen good sleepers were instructed to respond to the second stimulus in a pair during waking sessions. In a non-response paradigm modified for sleep, participants then fell asleep while tones played. As expected, N1 decreased and P2 increased in amplitude systematically with the loss of consciousness at sleep onset; the CNV was increasingly more positive. Sleep onset latency was correlated with the amplitude of the CNV. The systematic attenuation of the CNV waveform at sleep onset and its absence in sleep indicates that anticipatory attention requires endogenous conscious control.     

RELAXATION TREATMENT OF PSEUDOINSOMNIA AND IDIOPATHIC INSOMNIA: AN ELECTROENCEPHALOGRAPHIC EVALUATION

Twenty-nine insomniacs underwent four consecutive sleep laboratory evaluations before and after receiving tension-release relaxation training, no-tension-release relaxation training, or no-treatment. On the basis of the discrepancy between subjective and EEG-defined measures of latency to sleep onset, subjects were classified as pseudoinsomniacs or idiopathic insomniacs. As predicted, tension-release relaxation was significantly more effective than the other two conditions on subjective sleep measures, regardless of insomnia subtype and on objective sleep measures only for idiopathic insomniacs. Subjective improvement was maintained at 12-month followup. Numerous differences between the two subtypes emerged on pretherapy and during-therapy measures distinct from the latency measures, but changes on those variables were unrelated to outcome improvement.     

Delayed Bedtimes Are Associated With More Severe Obsessive-Compulsive Symptoms in Intensive Residential Treatment

Delays in behavioral and biological circadian rhythms (e.g., sleep timing, melatonin secretion) are found more frequently in individuals with severe and treatment-resistant obsessive-compulsive disorder (OCD). In recent years, it has been documented that these delays in behavioral and biological circadian rhythms are associated with more severe OCD symptoms and poorer response to some OCD treatments. This study examined self-reported sleep behaviors in individuals taking part in an intensive treatment for OCD and the relations between these and OCD symptoms (both at admission to and discharge from the treatment program). Replicating previous findings in less severe populations, delayed sleep phases were relatively common in this group and later bedtimes were associated with more severe OCD symptoms at admission. Sleep onset latency and sleep duration were not associated with OCD symptom severity at admission. Later bedtimes were not associated with self-reported depression or worry symptom severity. There was no evidence of sleep behaviors affecting change in OCD symptoms from admission to discharge from treatment—however, later bedtimes at admission were associated with more severe OCD symptoms at admission and discharge from treatment. There was no evidence of sleep onset latency or sleep duration having a similar predictive effect. More severe OCD symptoms at admission were also associated with later bedtimes at admission and discharge from treatment. These bidirectional predictive relations between late bedtimes and OCD symptoms were of small effect size but support the potential value of evaluating sleep timing in individuals with severe and/or treatment-resistant OCD.     

The management of unwanted pre-sleep thoughts in insomnia: distraction with imagery versus general distraction

Insomniacs commonly complain that they are unable to get to sleep at night due to unwanted thoughts, worries and concerns. The present study investigated whether brief training in identifying and elaborating an interesting and engaging imagery task for use during the pre-sleep period can reduce unwanted pre-sleep cognitive activity and sleep onset latency. Forty one people with insomnia were given one of three instructional sets to follow on the experimental night; instructions to distract using imagery, general instructions to distract, or no instructions. Based on previous findings reported by Salkovskis & Campbell (1994) 'Behaviour Research and Therapy 32 (1994) 1' and ironic control theory (Wegner, 1994) 'Psychological Review 101 (1994) 34', it was predicted that (1) "imagery distraction" would be associated with shorter sleep onset latency and less frequent and distressing pre-sleep cognitive activity compared to the "no instruction" group and that (2) "general distraction" would be associated with longer sleep onset latency and more frequent and distressing pre-sleep cognitive activity compared to the "no instruction" group. Support was found for the first but not the second prediction. The success of the "imagery distraction" task is attributed to it occupying sufficient "cognitive space" to keep the individual from re-engaging with thoughts, worries, and concerns during the pre-sleep period. In addition, "imagery distraction" involved a very specific alternative cognitive task hence the operating process was given a feature positive search, conditions where mental control is likely to be achieved.     

Social factors and the psychobiology of depression: relations between life stress and rapid eye movement sleep latency.

We examined psychosocial factors (i.e., life stress) and biological factors (i.e., REM sleep latency) that are hypothesized to be of complementary importance for defining depressive subtypes in a sample of 61 nonpsychotic, endogenous major depressives. Subjects were evaluated on several diagnostic scales for life stress, on electroencephalographic sleep data, and on 2 symptom measures for depression. As predicted, persons with severe stress that occurred shortly before depression onset had essentially normal REM latency values; patients without such stress had reduced REM latency values. Both stress and REM latency were also associated with greater severity of self-reported depressive symptoms. Alternative explanations of these findings are discussed, with particular emphasis on different roles of pre-onset and post-onset stressors.     

Effects of total sleep loss on sleep tendency.

Effects of two nights of sleep loss were assessed in six young adult (18--21 yr.) volunteers (2 women, 4 men). Performance on the Wilkinson Addition Test fell significantly below baseline values during the sleep-loss procedure and recovered after one or two full nights of sleep. Performance on a Serial Alternation Task also declined during sleep loss. Mood and sleepiness, assessed by subjective self-rating scales, showed a significantly less positive mood and a greater degree of sleepiness during sleep loss, with a recovery to baseline levels after one full night of sleep. Sleep tendency, measured at 2-hr. intervals during all waking periods, was assessed using an objective measure of latency to sleep onset, the Sleep Latency Test. The scores fell to about 1 min. at 0600 on the first night of sleep loss and remained at similarly low values throughout the sleep loss period. After one night of recovery sleep the scores remained significantly below baseline levels, which were not achieved until after the second recovery night. The multiple sleep latency test appears to be a valuable operationally defined tool for measuring daytime sleepiness.     

The effect of a delayed weekend sleep pattern on sleep and morning functioning

Abstract

It is a common practice for young adults to delay their weekend sleep schedule. The present study was designed to assess the effect of this sleep pattern on the sleep of Sunday night and the functioning of Monday morning. The sleep schedules of 30 young adults were manipulated for 2 consecutive weeks. In the Habitual-Sleep (HS) week, subjects followed their habitual sleep schedule throughout the week; in the Delayed-Sleep (DS) week, subjects' sleep schedule on Friday and Saturday nights were delayed by two hours. Compared to the HS week, subjects showed significantly lower subjective sleepiness near bedtime and trends of longer sleep onset latency on Sunday night in the DS week. In addition, there was both lowered cognitive performance and overall mood rating on Monday morning in the DS week. The delayed weekend sleep pattern contributes to Sunday night insomnia and the Monday morning “blues”.     

The effectiveness of various treatment techniques on different degrees and durations of sleep-onset insomnia

Mild and moderate insomniacs were randomly assigned to one of five group therapy conditions: relaxation without muscle-tension, stimulus control plus relaxation without muscletension, placebo, self-monitoring, and waiting list. Mild insomniacs were differentiated according to the duration of their sleep disturbance. Insomniacs were told that improvement would not be noticeable until after the final therapy session. During this counterdemand period, the two relaxation groups showed significantly greater decreases in sleep onset latency than the control conditions. In addition, it appeared that duration affected treated outcome. The effectiveness of treatment packages and self-monitoring in alleviating insomnia is briefly discussed.     

Comparative meta-analysis of behavioral interventions for insomnia and their efficacy in middle-aged adults and in older adults 55+ years of age.

Meta-analyses support the effectiveness of behavioral interventions for the treatment of insomnia, although few have systematically evaluated the relative efficacy of different treatment modalities or the relation of old age to sleep outcomes. In this meta-analysis of randomized controlled trials (k = 23), moderate to large effects of behavioral treatments on subjective sleep outcomes were found. Evaluation of the moderating effects of behavioral intervention type (i.e., cognitive-behavioral treatment, relaxation, behavioral only) revealed similar effects for the 3 treatment modalities. Both middle-aged adults and persons older than 55 years of age showed similar robust improvements in sleep quality, sleep latency, and wakening after sleep onset. A research agenda is recommended to examine the mechanisms of action of behavioral treatments on sleep with increased attention to the high prevalence of insomnia in older individuals.     

Developmental changes of parental-reported sleep disturbance symptoms in children with attention deficit disorder

The primary goal of this retrospective study was to assess parental report of current sleep disorders in school-aged attention deficit disorder (ADD) children, as well as recalled sleep problems from when the children were infants (0–12 months) and toddlers (1–3 years). Results of a sleep questionnaire completed by mothers of 48 ADD children and a comparison group of 30 patients with school problems indicate that ADD children were perceived to have significantly more sleep problems and that these problems had onset in infancy. Specific items in the questionnaire which were increased included latency to sleep onset of more than 30 min at least 3 nights per week, fatigue upon awakening, and recall of nightmares. Pediatric clinicians should be alert to possible sleep disorders in children suspected of attention disorders and should consider sleep hygiene measures as a component of treatment.     

A pilot study of cognitive-behavioral therapy of insomnia in people with mild depression

In some cases, insomnia and depression may have a reciprocal relationship, in which each aggravates and maintains the other. To test the hypothesis that reduction of insomnia would result in reduction of depression in patients (N=10) with both disorders, a repeated-measures design was used comparing depression and insomnia levels before and after 6 sessions of cognitive-behavioral therapy of insomnia. Posttreatment, 100% of completers (n=8) had a normalized sleeping pattern, and 87.5% had normalized depression scores. Significant posttreatment improvement was seen in sleep onset latency (-31 min), wake time after sleep onset (-24 min), total sleep time (+65 min), sleep efficiency (+14%), and sleep quality (+19%), which was maintained at 3-month follow-up. A decreasing trend occurred in depression scores from pre- to posttreatment, which reached significance at 3-month follow-up. Intent-to-treat analyses showed similar results.     

Correcting distorted perception of sleep in insomnia: a novel behavioural experiment?

Patients with primary insomnia overestimate their sleep onset latency (SOL) and underestimate their total sleep time (TST). The present study aimed to test the utility of a novel behavioural experiment designed to correct distorted perception of sleep among patients diagnosed with primary insomnia. Individuals with primary insomnia were asked to wear an actigraph and keep a sleep diary for three nights. On the following day, half were shown the discrepancy between the data recorded on the actigraph and their sleep diary (Shown-Discrepancy Group), the other half were not shown the discrepancy (No-Demonstration Group). Participants were then asked to wear the actigraph and keep a sleep diary for three further nights. Following the behavioural experiment, the Shown-Discrepancy Group estimated their SOL more accurately and reported less anxiety and preoccupation about sleep compared to the No-Demonstration Group. The theoretical and clinical implications of these findings are discussed.