Metamemory beliefs and episodic memory in obstructive sleep apnea syndrome

This study assessed metamemory and its role in actual episodic memory performance in 26 patients with obstructive sleep apnea syndrome and 27 healthy controls. Metamemory knowledge and memory beliefs were assessed using the Metamemory Inventory in Adulthood. Episodic memory performance was investigated with the Remember/Know paradigm. Subjective sleepiness was evaluated. Patients underwent a polysomnographic assessment. In contrast to the control group's more stable memory beliefs, patients self-assessed their memory as declining across time, and felt more anxious about their memory. There was only a modest difference between patients' self-perceptions of their memory capacities and those of the control group, but patients' actual memory performance was strongly disturbed. While the latter was significantly correlated with severity of obstructive sleep apnea, scores on the Metamemory Inventory in Adulthood scales were not correlated with physiological measures, subjective sleepiness, or episodic memory performance. Obstructive sleep apnea may affect prefrontal cortex functioning and hence the ability to assess one's own memory impairment.     

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.     

Cognitive-behavioral therapy of insomnia: A clinical case series study of patients with co-morbid disorders and using hypnotic medications

Cognitive-behavioral therapy for insomnia (CBTi) has demonstrated considerable efficacy within randomized clinical trials and case-series designs. This case-series study in a community sleep medicine clinic assessed the effectiveness of an eight-session CBTi protocol chronic insomnia patients who were allowed to continue their use of hypnotics (intent-to-treat n = 48), administered by a clinical psychology doctoral student receiving training and supervision in CBTi by a behavioral sleep medicine certified clinician. Outcome measures included daily sleep diaries, self-report measures on insomnia severity, dysfunctional beliefs and attitudes about sleep, daytime sleepiness, as well as medication usage. Patients showed significant improvements in sleep onset latency, wake time after sleep onset, sleep efficiency, insomnia severity, and dysfunctional sleep beliefs from pre- to post-treatment. No changes were seen in daytime sleepiness - patients were not excessively sleepy either before or after treatment. Use of sleep medication declined significantly from 87.5% pre-treatment to 54% post-treatment, despite no active efforts to encourage patients to withdraw. Results demonstrate that a CBTi conducted in a community sleep medicine clinic with patients not required to discontinue sleep-related medications can have similar effects as therapy delivered among those not on medication.     

Psychological status and levels of sleepiness-alertness among patients with insomnia

Are symptoms of daytime sleepiness relevant among patients with insomnia? Patients with insomnia frequently report daytime consequences secondary to their difficulty initiating and maintaining sleep. The purpose of this study was to determine the frequency of daytime sleepiness as defined by a self-reported measure of daytime sleepiness (the Epworth Sleepiness Scale). In addition, the study characterized the patients' psychological status using the Symptom Checklist-90-Revised. The study corroborated a relatively high frequency of excessive daytime sleepiness and psychiatric conditions among patients with insomnia. Furthermore, the results of the study suggest variation in psychological distress levels, according to the different levels of sleepiness/alertness.     

Sleep-competing behaviours among Australian school-attending youth: Associations with sleep,mental health and daytime functioning

Sleep problems are highly prevalent among school-attending youth, and impact on school performance and outcomes. Sleep-competing behaviours are likely factors in the inadequate sleep time and related functional outcomes observed in this population. We examined a range of sleep-competing behaviours and their associations with sleep variables in Australian school-attending youth. We also assessed whether these behaviours indirectly affected mental health and daytime functioning through poorer sleep quality. A total of 353 school-attending youth (mean age = 14.6 years, 53% female) were recruited from high schools in Australia, and completed a range of self-report measures. Approximately 50% of the youth obtained sub-optimal levels of sleep and reported having a problematically long sleep onset latency. Sleep competing behaviours, related and unrelated to electronic media use, were reported as occurring frequently, and were associated with a range of sleep variables. These behaviours were also related to poorer mental health and daytime sleepiness, with this association explained by indirect effects through sleep quality. Sleep-competing behaviours are prevalent on school nights in Australian youth, and may have adverse associations with mental health and functioning. Prevention and intervention programs might address the risk factors identified in the current study.     

Sleep patterns and sleep disruptions in school-age children

This study assessed the sleep patterns, sleep disruptions, and sleepiness of school-age children. Sleep patterns of 140 children (72 boys and 68 girls; 2nd-, 4th-, and 6th-grade students) were evaluated with activity monitors (actigraphs). In addition, the children and their parents completed complementary sleep questionnaires and daily reports. The findings reflected significant age differences, indicating that older children have more delayed sleep onset times and increased reported daytime sleepiness. Girls were found to spend more time in sleep and to have an increased percentage of motionless sleep. Fragmented sleep was found in 18% of the children. No age differences were found in any of the sleep quality measures. Scores on objective sleep measures were associated with subjective reports of sleepiness. Family stress, parental age, and parental education were related to the child's sleep-wake measures.     

Effects of acute sleep restriction on behavior, sustained attention, and response inhibition in children.

This study examined the effects of acute sleep restriction on the day-time behavior and performance of healthy children and adolescents. 82 participants (8 to 15 years of age) completed 5 nights of baseline sleep and were randomly assigned to Optimized (10 hr.) or Restricted (4 hr.) sleep for an overnight lab visit. Behavior, performance, and sleepiness were assessed the following day. Sleep restriction was associated with shorter daytime sleep latency, increased subjective sleepiness, and increased sleepy and inattentive behaviors but was not associated with increased hyperactive-impulsive behavior or impaired performance on tests of response inhibition and sustained attention. Results are discussed in terms of current theories regarding effects of inadequate or disturbed sleep among children and adolescents.     

Misperception of sleep can adversely affect daytime functioning in insomnia

This experiment was designed to investigate the relationship between subjective perception of sleep and daytime processes in primary insomnia. Twenty-two individuals with primary insomnia received positive or negative feedback about their sleep, immediately on waking, on three consecutive mornings. The positive feedback was that last night's sleep was good quality. The negative feedback was that last night's sleep was poor quality. Objective sleep on each of the three nights was estimated by actigraphy and did not differ across the three nights or the two feedback conditions. Negative feedback (based on 32 nights of data) was associated with more negative thoughts, sleepiness, monitoring for sleep-related threat, and safety behaviours during the day, relative to positive feedback (based on 34 nights of data). These results indicate that the impaired daytime functioning reported by insomnia patients is maintained, at least in part, by subjective perception of sleep.     

The role of sleep-related beliefs to improvement in early cognitive behavioral therapy for insomnia

The aim of this investigation was to examine whether sleep-related beliefs, and reductions in such beliefs and attitudes, were related to clinical improvements in sleep and daytime symptoms after cognitive behavioral therapy (CBT). In total, 64 patients with a short history of insomnia (3-12 months) who had participated in a randomized controlled trial with a 1-year follow-up and received CBT were included. With stepwise multiple regression analyses, sleep-related beliefs were linked to clinical improvements in sleep (five outcomes) and daytime symptoms (seven outcomes). Results indicated that sleep-related beliefs played a small predictive role in clinical improvements in sleep and daytime symptoms after CBT group treatment. Sleep-related beliefs were predictive of treatment response only with regard to sleep efficiency and sleepiness. Reductions in sleep-related beliefs were, however, differently related to improvements in sleep and daytime symptoms. Reductions in such beliefs were consistently linked to improvements in daytime symptoms (7-14% of the variance) but not to sleep improvements (except for sleep quality). In all, this might suggest that sleep-related beliefs play a slightly different role in insomnia than previously envisioned.     

Psychiatric diagnoses of patients visiting a sleep disorder clinic due to dyssomnias

This study analyzed the demographic characteristics and psychiatric diagnoses of 90 consecutive patients who visited a sleep disorder clinic in Taiwan with complaints of insomnia (difficulty initiating or maintaining sleep, or nonrestorative sleep) or hypersomnia (excessive sleepiness as evidenced by either prolonged sleep episodes or daytime sleep episodes that occur almost daily). All subjects were interviewed using a sleep disturbance questionnaire and the structured Mini-International Neuropsychiatric Interview supplemented by the DSM-IV criteria for psychiatric diagnoses. Among 90 patients, 79 were classified as having insomnia and 11 had hypersomnia. 53 patients also had psychiatric diagnoses other than sleep disorders. Patients with insomnia had a significantly higher rate of comorbidities with other psychiatric diagnoses (65.8%) than did subjects with hypersomnia (9.1%). These results emphasize the importance of psychiatric evaluation of patients with complaints of sleep disturbance.     

Are insomniacs sleepy during the day? A pupillometric assessment.

A biodevelopmental model of insomnia is articulated specifying coordinated nighttime (disturbed sleep pattern) and daytime (no excessive daytime sleepiness) characteristics defining an insomnoid classification in at-risk groups: short sleepers and older adults. Pupillometry is proposed as a useful means of discriminating degree of daytime sleepiness to aid in the differential diagnosis of insomnia and insomnoid states, and the present study tested the discriminative validity of this approach. Noninsomniac (n = 34) and insomniac (n = 29) college students submitted to four 10 min pupillometry sessions tracking daytime sleepiness from morning arising to bedtime. Pupil diameter proved to be an able discriminator of these two groups though substantial overlap of the two distributions was also noted. The results supported the sensitivity of pupillometry in detecting daytime sleepiness, but yielded alternative interpretations. We observed statistical differentiation in insomniac and noninsomniac daytime sleepiness, but substantial, functional overlap between these groups. Assessment and treatment implications arising from the biodevelopmental model were hypothesized.     

A daytime nap containing solely non-REM sleep enhances declarative but not procedural memory

The specialized role that sleep-specific brain physiology plays in memory processing is being rapidly clarified with a greater understanding of the dynamic, complex, and exquisitely orchestrated brain state that emerges during sleep. Behaviorally, the facilitative role of non-REM (NREM) sleep (primarily slow wave sleep) for declarative but not procedural memory performance in humans has been demonstrated in a number of nocturnal sleep studies. However, subjects in these studies were tested after periods of sleep that contained REM sleep in addition to NREM sleep, and comparison wake groups were subjected to mild sleep deprivation. To add some clarity to the findings of these nocturnal studies, we assessed performance on declarative and procedural memory tasks following a daytime training-retest interval containing either a short nap that included NREM without REM sleep, or wakefulness. Consistent with previous findings we show that, after a comparatively brief sleep episode, subjects that take a nap improve more on a declarative memory task than subjects that stay awake, but that improvement on a procedural memory task is the same regardless of whether subjects take a nap or remain awake. Slow wave sleep was the only sleep parameter to correlate positively with declarative memory improvement. These findings are discussed with reference to the general benefits of napping and within the broader context of a growing literature suggesting a role for NREM-specific physiology for the processing of declarative memory.     

Epidemiology of Insomnia in College Students: Relationship With Mental Health,Quality of Life,and Substance Use Difficulties

The purpose of this study was to evaluate the prevalence and correlates of insomnia using rigorous diagnostic criteria and a comprehensive assessment battery. In a large sample (N = 1,074) of college students (mean age 20.39 years), participants were asked to complete a week-long sleep diary and comprehensive questionnaire packet assessing recommended daytime functioning domains (i.e., fatigue, quality of life, depression, anxiety, stress, academic performance, substance use) during the academic year. A significant portion of this sample of college students met proposed DSM-5 criteria for chronic insomnia (9.5%). The chronic insomnia group reported significantly worse sleep, fatigue, depression, anxiety, stress, and quality of life, and greater hypnotic and stimulant use for sleep problems. There were no differences between groups on excessive daytime sleepiness, academic performance, or substance use. This was a rigorous and comprehensive assessment of the prevalence and psychosocial correlates of insomnia. Insomnia is a significant problem in college students and should be regularly assessed. More research is also needed to guide treatment in this population.     

Effects of acute simulated microgravity on nocturnal sleep, daytime vigilance, and psychomotor performance: comparison of horizontal and 6 degrees head-down bed rest

This study examined the effect of acute simulated microgravity on nocturnal sleep, daytime vigilance, and psychomotor performance. Each of 7 volunteers were maintained for 3 days of head-down and horizontal bed rest in a counter-balanced design. Assessment measures were polysomnographic recordings on the first night and performance on psychophysiological tasks on the second day involving subjective and objective vigilance, P300, simple reaction time tasks, and dual performance tasks. No clear difference in sleep structure was observed between the head-down and horizontal conditions, except for a slight decrease in Stage 4 for head-down. Both subjective and objective daytime vigilance, P300, and the simple RT task showed no statistical difference, although tracking performance on the dual task showed deterioration at 10:00 for the head-down condition. These results suggest that nocturnal sleep, daytime vigilance, and psychophysiological functions were not disturbed in head-down sleep conditions, although there was a mild deterioration of higher attentional function in the morning.     

Cognitive-behavioural Analysis and 1 reatment ot Insomnia

Abstract

Insomnia is a condition characterized by subjective complaints of insufficient sleep and poor daytime functioning. Objective measures of sleep and daytime functioning, however, seldom show evidence of a similar degree of dysfunction. Most insomniacs, for example, do not suffer from sleep deprivation or daytime sleepiness. This discrepancy between subjective and objective measures of sleep and daytime functioning suggests that cognitive factors may play a central role in persistent insomnia. In particular, it is argued that fears about insufficient sleep and its adverse daytime consequences tend to interfere with sleep, thereby causing a vicious cycle which serves to maintain the insomnia. It is also argued that perfectionist standards and other dysfunctional beliefs may predispose people to these kinds of fears. Finally, existing models for cognitive-behavioural treatment of insomnia are criticized for being almost exclusively focused on the night-time aspects of insomnia. If insomnia is maintained by various kinds of vicious cycles involving fears, beliefs, and standards with regard to daytime functioning, these daytime aspects of insomnia should receive more attention in cognitive-behavioural treatment.     

Correlates of general quality of life are different in patients with primary insomnia as compared to patients with insomnia and psychiatric comorbidity

Chronic insomnia is known to have a negative influence on quality of life (QOL). To date, most studies on chronic insomnia have focused on health-related aspects of QOL. General QOL, which is a different construct, has not been studied in detail. Moreover, it is not known which factors are associated with general QOL in insomnia, and whether the presence of mental disorders, a condition known as comorbid insomnia, affects these variables. The present study focused on identifying sleep and psychosocial variables that might be associated with general QOL in primary and comorbid insomnia. Personality traits, coping variables, anxiety and depressive symptoms, fatigue and subjective sleep variables were assessed in 218 consecutive well-characterized patients with primary and comorbid insomnia, referred to a third line centre for sleep medicine. In primary insomnia, higher extraversion and lower discrepancies in social support were associated with higher QOL. Surprisingly, insomnia severity was not significantly associated with QOL in this group. However, lower fatigue, which can be seen as an important daytime consequence of insomnia was correlated with higher QOL in patients with primary insomnia. In both insomnia groups, low anxiety and depressive symptoms and low fatigue were associated with higher general QOL. In contrast with the primary insomnia group, lower insomnia severity was correlated with higher QOL in patients with comorbid insomnia. These results stress the importance of assessing and treating daytime fatigue in insomnia. In primary insomnia, improving social support might be an important treatment goal. Furthermore, this study supports the concept that treatment of insomnia should not be neglected in patients with comorbid insomnia. Indeed, both insomnia and indices of psychiatric disease are strongly associated with general QOL in this condition.     

What subjective experiences determine the perception of falling asleep during sleep onset period?

Sleep onset is associated with marked changes in behavioral, physiological, and subjective phenomena. In daily life though subjective experience is the main criterion in terms of which we identify it. But very few studies have focused on these experiences. This study seeks to identify the subjective variables that reflect sleep onset. Twenty young subjects took an afternoon nap in the laboratory while polysomnographic recordings were made. They were awakened four times in order to assess subjective experiences that correlate with the (1) appearance of slow eye movement, (2) initiation of stage 1 sleep, (3) initiation of stage 2 sleep, and (4) 5 min after the start of stage 2 sleep. A logistic regression identified control over and logic of thought as the two variables that predict the perception of having fallen asleep. For sleep perception, these two variables accurately classified 91.7% of the cases; for the waking state, 84.1%.     

The Chronotype-Academic Performance Model (CAM): Daytime sleepiness and learning motivation link chronotype and school performance in adolescents

Many adolescents experience a discrepancy between their biological time, which is shifted toward eveningness, and early school starting times. Due to this social jetlag, eveningness is negatively correlated with school performance. On the basis of the here presented data, we derived a model for the association of chronotype and school performance, the Chronotype-Academic Performance Model (CAM), including daytime sleepiness and achievement motivation as mediating factors. The sample comprised N = 273 adolescents aged 14–16 years. Circadian preference, daytime sleepiness, learning and achievement motivation, and information about participants’ last school certificate were assessed online. Chronotype was not directly related to academic performance, but was mediated by daytime sleepiness and learning motivation. Morning-orientation was negatively associated with daytime sleepiness and positively with learning motivation, which, in turn, affected performance. In evening-types, we found the strongest association between sleepiness and refusal to work. The CAM suggests that chronotype may not directly influence academic performance, but be mediated by daytime sleepiness and learning motivation. Evening types seem to be at high risk to suffer from daytime sleepiness and to display dysfunctional attitudes toward work. Measures of reducing sleepiness and modifying attitudes toward academic achievement might attenuate the disadvantages of evening-types due to social jetlag.     

The relationship between sleep problems and working memory in children born very preterm

In two studies, the relationship between sleep and working memory performance was investigated in children born very preterm (i.e., gestation less than 32 weeks) and the possible mechanisms underlying this relationship. In Study 1, parent-reported measures of snoring, night-time sleep quality, and daytime sleepiness were collected on 89 children born very preterm aged 6 to 7 years. The children completed a verbal working memory task, as well as measures of processing speed and verbal storage capacity. Night-time sleep quality was found to be associated with verbal working memory performance over and above the variance associated with individual differences in processing speed and storage capacity, suggesting that poor sleep may have an impact on the executive component of working memory. Snoring and daytime sleepiness were not found to be associated with working memory performance. Study 2 introduced a direct measure of executive functioning and examined whether sleep problems would differentially impact the executive functioning of children born very preterm relative to children born to term. Parent-reported sleep problems were collected on 43 children born very preterm and 48 children born to term (aged 6 to 9 years). Problematic sleep was found to adversely impact executive functioning in the very preterm group, while no effect of sleep was found in the control group. These findings implicate executive dysfunction as a possible mechanism by which problematic sleep adversely impacts upon cognition in children born very preterm, and suggest that sleep problems can increase the cognitive vulnerability already experienced by many of these children.     

Daytime naps improve motor imagery learning

Sleep is known to contribute to motor memory consolidation. Recent studies have provided evidence that a night of sleep plays a similar functional role following motor imagery (MI), while the simple passage of time does not result in performance gains. Here, we examined the benefits of a daytime nap on motor memory consolidation after MI practice. Participants were trained by MI on an explicitly known sequence of finger movements at 11:00. Half of the participants were then subjected (at 14:00) to either a short nap (10 min of stage 2 sleep) or a long nap (60–90 min, including slow wave sleep and rapid eye movement sleep). We also collected data from both quiet and active rest control groups. All participants remained in the lab until being retested at 16:00. The data revealed that a daytime nap after imagery practice improved motor performance and, therefore, facilitated motor memory consolidation, as compared with spending a similar time interval in the wake state. Interestingly, the results revealed that both short and long naps resulted in similar delayed performance gains. The data might also suggest that the presence of slow wave and rapid eye movement sleep does not provide additional benefits for the sleep-dependent motor skill consolidation following MI practice.