Cardiovascular autonomic dysfunction in insomnia patients with objective short sleep duration

Two phenotypes have been proposed: insomnia with objective near‐normal sleep duration, related to increased psychological symptoms, and insomnia with objective short sleep duration, associated with cardiometabolic morbidity. Reduced heart rate variability has also been implicated in the pathophysiology of cardiometabolic disease; however, there are little data on whether cardiovascular function differs between patients with objective short sleep duration and near‐normal sleep duration. Participants (M_age = 49.9 ± 11.3 years; 62.8% female) were 180 adults with chronic insomnia (M_duration = 15.7 ± 13.6). Objective sleep duration was based on total sleep time averaged across two consecutive nights of polysomnography and subjective sleep duration was based on 2‐week sleep diaries. The sample was divided into two groups, with sleep duration shorter (polysomnography‐total sleep time: n = 46; sleep diary: n = 95) or equal/longer (polysomnography‐total sleep time: n = 134; sleep diary: n = 85) than 6 hr. Electrocardiogram data derived from polysomnography were used to obtain heart rate and heart rate variability during stage 2 (N2) and rapid eye movement sleep. Heart rate variability measures included absolute and normalized high‐frequency component, an index of parasympathetic activation, and the ratio of low‐ to high‐frequency (LF/HF ratio), an index of sympathovagal balance. After controlling for covariates (e.g., co‐morbidity), patients with objective short sleep duration had reduced high‐frequency (p < .05) and elevated low‐frequency/high‐frequency ratio (p = .036) and heart rate (p = .051) compared with patients with near‐normal sleep duration. No differences were observed between phenotypes when subjective sleep duration was used. Insomnia patients with objective short sleep duration showed significantly dampened parasympathetic activation and increased sympathovagal imbalance relative to their counterparts with near‐normal sleep duration. These findings highlight the importance of treating insomnia, as treatment may reduce the risk of cardiovascular disease.     

Sleep patterns and insomnia in a large population‐based study of middle‐aged and older adults: The Tromsø study 2015–2016

Epidemiological studies assessing adult sleep duration have yielded inconsistent findings and there are still large variations in estimation of insomnia prevalence according to the most recent diagnostic criteria. Our objective was to describe sleep patterns in a large population of middle‐aged and older adults, by employing accurate measures of both sleep duration and insomnia. Data stem from the Tromsø Study (2015–2016), an ongoing population‐based study in northern Norway comprising citizens aged 40 years and older (n = 21,083, attendance = 64.7%). Sleep parameters were reported separately for weekdays and weekends and included bedtime, rise time, sleep latency and total sleep time. Insomnia was defined according to recent diagnostic criteria (International Classification of Sleep Disorders; ICSD‐3). The results show that 20% (95% confidence interval,19.4–20.6) fulfilled the inclusion criteria for insomnia. The prevalence was especially high among women (25%), for whom the prevalence also increased with age. For men, the prevalence was around 15% across all age groups. In all, 42% of the women reported sleeping <7 hr (mean sleep duration of 7:07 hr), whereas the corresponding proportion among males was 52% (mean sleep duration of 6:55 hr). We conclude that the proportion of middle‐aged and older adults not getting the recommended amount of sleep is worryingly high, as is also the observed prevalence of insomnia. This warrants attention as a public health problem in this population.     

Subjective insomnia symptoms and sleep duration are not related to hypothalamic–pituitary–adrenal axis activity in older adults

Insomnia symptoms are highly prevalent in depressed older adults. This study investigates the association between hypothalamic–pituitary–adrenal (HPA) axis activity and symptoms of insomnia, respectively, sleep duration among 294 depressed and 123 non‐depressed older adults of the Netherlands Study of Depression in Older people (NESDO) study. Insomnia symptoms were defined as clinically relevant when having a score ≥ 10 points on the Women's Health Initiative Insomnia Rating Scale (WHIIRS). Sleep duration was categorized in short (≤ 6 h per night), normal (7–8 h per night) and long (≥ 9 h per night) duration. Salivary cortisol levels were used to assess the following cortisol parameters for HPA axis activity: area under the curve with respect to the increase (AUCi) and to the ground (AUCg), diurnal slope, evening cortisol level and dexamethasone suppression ratio. Clinically relevant insomnia symptoms were present in 46% of the participants. Thirty‐two per cent of the participants were short sleepers, whereas 16% were long sleepers. However, univariate analyses showed no differences in any of the HPA axis parameters between people with and without insomnia symptoms or between the three groups with different sleep duration. In addition, no significant interaction was found between a diagnosis of depression or the severity of depressive symptoms and any of the cortisol parameters in relation to insomnia symptoms or sleep duration.     

Subjective–objective sleep discrepancy among older adults: associations with insomnia diagnosis and insomnia treatment

Discrepancy between subjective and objective measures of sleep is associated with insomnia and increasing age. Cognitive behavioural therapy for insomnia improves sleep quality and decreases subjective–objective sleep discrepancy. This study describes differences between older adults with insomnia and controls in sleep discrepancy, and tests the hypothesis that reduced sleep discrepancy following cognitive behavioural therapy for insomnia correlates with the magnitude of symptom improvement reported by older adults with insomnia. Participants were 63 adults >60 years of age with insomnia, and 51 controls. At baseline, participants completed sleep diaries for 7 days while wearing wrist actigraphs. After receiving cognitive behavioural therapy for insomnia, insomnia patients repeated this sleep assessment. Sleep discrepancy variables were calculated by subtracting actigraphic sleep onset latency and wake after sleep onset from respective self‐reported estimates, pre‐ and post‐treatment. Mean level and night‐to‐night variability in sleep discrepancy were investigated. Baseline sleep discrepancies were compared between groups. Pre–post‐treatment changes in Insomnia Severity Index score and sleep discrepancy variables were investigated within older adults with insomnia. Sleep discrepancy was significantly greater and more variable across nights in older adults with insomnia than controls, P ≤ 0.001 for all. Treatment with cognitive behavioural therapy for insomnia was associated with significant reduction in the Insomnia Severity Index score that correlated with changes in mean level and night‐to‐night variability in wake after sleep onset discrepancy, P < 0.001 for all. Study of sleep discrepancy patterns may guide more targeted treatments for late‐life insomnia.     

Association between objective sleep measures and cognitive performance: a cross-sectional analysis in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) study

Sleep disturbances often co-exist, which challenges our understanding of their potential impact on cognition. We explored the cross-sectional associations of insomnia and objective measures of sleep with cognitive performance in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) study stratified by middle-aged and older adults. Participants aged ≥55 years underwent cognitive evaluations, polygraphy for 1 night, and actigraphy for 7 days. Insomnia was evaluated using the Clinical Interview Scheduled Revised. Obstructive sleep apnea (OSA) and short sleep duration (SSD) were defined by an apnea–hypopnea index (AHI) of ≥15 events/h and <6 h/ night, respectively. In 703 participants (mean [SD] age 62 [6] years, 44% men), cognition was evaluated using a 10-word list, verbal fluency, and trail-making tests. The frequencies of insomnia, SSD, and OSA were 11%, 24%, and 33%, respectively. In all, 4% had comorbid OSA and insomnia, and 11% had both OSA and SSD. Higher wake after sleep onset (β = −0.004, 95% confidence interval [CI] −0.008, −0.001) and the number of awakenings (β = −0.006, 95% CI −0.012, −0.001) were associated with worse verbal fluency performance. Compared to those without insomnia, older participants with insomnia had worse global performance (β = −0.354, 95% CI −0.671, −0.038). Insomnia was an effect modifier in the associations between AHI and executive function performance (p for the interaction between insomnia and AHI = 0.004) and between oxygen saturation <90% and memory performance (p for the interaction between insomnia and oxygen saturation = 0.02). Although some associations between sleep measures and cognition were significant, they should be considered with caution due to the large sample size and multiple testing performed in this study.     

Associations between sleep duration and cognitive impairment in mild cognitive impairment

The prevalence of mild cognitive impairment (MCI) increases among elderly people and is associated with a high risk of dementia. Identifying factors that may contribute to the progress of MCI to dementia is critical. The objective of this study was to examine the association of objective sleep with cognitive performance in MCI patients. A subsample of 271 participants with a diagnosis of probable Alzheimer's disease (AD; N = 50) or mild cognitive impairment (MCI; N = 121) and 100 persons who were not cognitively impaired (NI) were recruited from a large population‐based cohort in the island of Crete, Greece (3140 older adults aged >60 years). All participants underwent extensive neuropsychiatric/neuropsychological evaluation and a 3‐day 24‐hr actigraphy. Objective sleep variables and their association with neuropsychological performance were examined across the three groups, controlling for demographics, body mass index, depression, sleep apnea symptoms and psychotropic medications. Patients with AD had significantly longer 24‐hr total sleep time (TST) compared to the MCI and NI groups. Long 24‐hr TST was associated with reduced performance on tasks that placed significant demands on attention and processing speed in the MCI group and the AD group. Elderly patients with MCI have similar objective sleep duration to normal controls, whereas AD patients sleep longer. Long sleep duration in patients with multidomain subtypes of MCI is associated with critical non‐memory cognitive domains. It appears that within the MCI group those that sleep longer have more severe cognitive impairment.     

Self‐administered acupressure for insomnia disorder: a pilot randomized controlled trial

Self‐administered acupressure has potential as a low‐cost alternative treatment for insomnia. To evaluate the short‐term effects of self‐administered acupressure for alleviating insomnia, a pilot randomized controlled trial was conducted. Thirty‐one subjects (mean age: 53.2 years; 77.4% female) with insomnia disorder were recruited from a community. The participants were randomized to receive two lessons on either self‐administered acupressure or sleep hygiene education. The subjects in the self‐administered acupressure group (n = 15) were taught to practise self‐administered acupressure daily for 4 weeks. The subjects in the comparison group (n = 16) were advised to follow sleep hygiene education. The primary outcome was the Insomnia Severity Index (ISI). Other measures included a sleep diary, Hospital Anxiety and Depression Scale and Short‐form Six‐Dimension. The subjects in the self‐administered acupressure group had a significantly lower ISI score than the subjects in the sleep hygiene education group at week 8 (effect size = 0.56, P = 0.03). However, this observed group difference did not reach a statistically significant level after Bonferroni correction. With regard to the secondary outcomes, moderate between‐group effect sizes were observed in sleep onset latency and wake after sleep onset based on the sleep diary, although the differences were not significant. The adherence to self‐administered acupressure practice was satisfactory, with 92.3% of the subjects who completed the lessons still practising acupressure at week 8. In conclusion, self‐administered acupressure taught in a short training course may be a feasible approach to improve insomnia. Further fully powered confirmatory trials are warranted.     

Insomnia symptoms and mortality: a register‐linked study among women and men from Finland,Norway and Lithuania

Evidence on the association between insomnia symptoms and mortality is limited and inconsistent. This study examined the association between insomnia symptoms and mortality in cohorts from three countries to show common and unique patterns. The Finnish cohort comprised 6605 employees of the City of Helsinki, aged 40–60 years at baseline in 2000–2002. The Norwegian cohort included 6236 participants from Western Norway, aged 40–45 years at baseline in 1997–1999. The Lithuanian cohort comprised 1602 participants from the City of Palanga, aged 35–74 years at baseline in 2003. Mortality data were derived from the Statistics Finland and Norwegian Cause of Death Registry until the end of 2012, and from the Lithuanian Regional Mortality Register until the end of 2013. Insomnia symptoms comprised difficulties initiating sleep, nocturnal awakenings, and waking up too early. Covariates were age, marital status, education, smoking, alcohol, physical inactivity, obesity, diabetes, cardiovascular diseases, depression, shift work, sleep duration, and self‐rated health. Cox regression analysis was used. Frequent difficulties initiating sleep were associated with all‐cause mortality among men after full adjustments in the Finnish (hazard ratio 2.51; 95% confidence interval 1.07–5.88) and Norwegian (hazard ratio 3.42; 95% confidence interval 1.03–11.35) cohorts. Among women and in Lithuania, insomnia symptoms were not statistically significantly associated with all‐cause mortality after adjustments. In conclusion, difficulties initiating sleep were associated with mortality among Norwegian and Finnish men. Variation and heterogeneity in the association between insomnia symptoms and mortality highlights that further research needs to distinguish between men and women, specific symptoms and national contexts, and focus on more chronic insomnia.     

Sleep patterns and insomnia among adolescents: a population‐based study

The aim of the current study was to examine sleep patterns and rates of insomnia in a population‐based study of adolescents aged 16–19 years. Gender differences in sleep patterns and insomnia, as well as a comparison of insomnia rates according to DSM‐IV, DSM‐V and quantitative criteria for insomnia (Behav. Res. Ther., 41 , 2003, 427), were explored. We used a large population‐based study in Hordaland county in Norway, conducted in 2012. The sample included 10 220 adolescents aged 16–18 years (54% girls). Self‐reported sleep measurements included bedtime, rise time, time in bed, sleep duration, sleep efficiency, sleep onset latency, wake after sleep onset, rate and frequency and duration of difficulties initiating and maintaining sleep and rate and frequency of tiredness and sleepiness. The adolescents reported short sleep duration on weekdays (mean 6:25 hours), resulting in a sleep deficiency of about 2 h. A majority of the adolescents (65%) reported sleep onset latency exceeding 30 min. Girls reported longer sleep onset latency and a higher rate of insomnia than boys, while boys reported later bedtimes and a larger weekday–weekend discrepancy on several sleep parameters. Insomnia prevalence rates ranged from a total prevalence of 23.8 (DSM‐IV criteria), 18.5 (DSM‐V criteria) and 13.6% (quantitative criteria for insomnia). We conclude that short sleep duration, long sleep onset latency and insomnia were prevalent in adolescents. This warrants attention as a public health concern in this age group.     

Insomnia with Objective Short Sleep Duration is Associated with Deficits in Neuropsychological Performance: A General Population Study

Study Objectives:

To examine the joint effect of insomnia and objective short sleep duration on neuropsychological performance.

Design:

Representative cross-sectional study.

Setting:

Sleep laboratory.

Participants:

1,741 men and women randomly selected from central Pennsylvania.

Interventions:

None.

Measurements:

Insomnia (n = 116) was defined by a complaint of insomnia with a duration ≥ 1 year and the absence of sleep disordered breathing (SDB), while normal sleep (n = 562) was defined as the absence of insomnia, excessive daytime sleepiness, and SDB. Both groups were split according to polysomnographic sleep duration into 2 categories: ≥ 6 h of sleep (“normal sleep duration”) and < 6 h of sleep (“short sleep duration”). We compared the groups'' performance on a comprehensive neuropsychological battery that measured processing speed, attention, visual memory, and verbal fluency, while controlling for age, race, gender, education, body mass index, and physical and mental health.

Results:

No significant differences were detected between insomniacs and controls. However, the insomnia with short sleep duration group compared to the control with normal or short sleep duration groups showed poorer neuropsychological performance in variables such as processing speed, set-switching attention, and number of visual memory errors and omissions. In contrast, the insomnia with normal sleep duration group showed no significant deficits.

Conclusions:

Insomnia with objective short sleep duration is associated with deficits in set-switching attentional abilities, a key component of the “executive control of attention.” These findings suggest that objective sleep duration may predict the severity of chronic insomnia, including its effect on neurocognitive function.

Citation:

Fernandez-Mendoza J; Calhoun S; Bixler EO; Pejovic S; Karataraki M; Liao D; Vela-Bueno A; Ramos-Platon MJ; Sauder KA; Vgontzas AN. Insomnia with objective short sleep duration is associated with deficits in neuropsychological performance: a general population study. SLEEP 2010;33(4):459-465.     

Actigraphic multi‐night home‐recorded sleep estimates reveal three types of sleep misperception in Insomnia Disorder and good sleepers

People with Insomnia Disorder tend to underestimate their sleep compared with polysomnography or actigraphy, a phenomenon known as paradoxical insomnia or sleep‐state misperception. Previous studies suggested that night‐to‐night variability could be an important feature differentiating subtypes of misperception. This study aimed for a data‐driven definition of misperception subtypes revealed by multiple sleep features including night‐to‐night variability. We assessed features describing the mean and dispersion of misperception and objective and subjective sleep duration from 7‐night diary and actigraphy recordings of 181 people with Insomnia Disorder and 55 people without sleep complaints. A minimally collinear subset of features was submitted to latent class analysis for data‐driven subtyping. Analysis revealed three subtypes, best discriminated by three of five selected features: an individual’s shortest reported subjective sleep duration; and the mean and standard deviation of misperception. These features were on average 5.4, ?0.0 and 0.5 hr in one subtype accommodating the majority of good sleepers; 4.1, ?1.4 and 1.0 hr in a second subtype representing the majority of people with Insomnia Disorder; and 1.7, ?2.2 and 1.5 hr in a third subtype representing a quarter of people with Insomnia Disorder and hardly any good sleepers. Subtypes did not differ on an individual’s objective sleep duration mean (6.9, 7.2 and 6.9 hr) and standard deviation (0.8, 0.8 and 0.9 hr). Data‐driven analysis of naturalistic sleep revealed three subtypes that markedly differed in misperception features. Future studies may include misperception subtype to investigate whether it contributes to the unexplained considerable individual variability in treatment response.     

Young poor sleepers mobilize extra effort in an easy memory task: evidence from cardiovascular measures

Insomniacs often complain of memory deficits, yet objective measures have not consistently corroborated their subjective impressions. A possible explanation for the partial gap between self‐report and behavioral measures of memory impairment is that insomniacs recruit extra effort to compensate for the consequences of poor sleep. The present study investigated whether subjective insomnia severity would predict objective effort mobilization, as indexed by cardiovascular measures, in an easy memory task. Seventy‐seven university students, mostly women, with a mean age of 22 years were asked to memorize four strings of four random letters in 5 min while cardiovascular measures were obtained. After taking an immediate recall test, participants completed the Insomnia Severity Index, the Multidimensional Fatigue Inventory, and a questionnaire on last night’s sleep and today’s fatigue. Finally, they were given a surprise delayed recall test. Analyses indicated that self‐reported insomnia severity was associated with an increase in systolic blood pressure during the learning phase. Regarding memory performance, insomnia severity was unrelated to immediate recall but related to a decrement in delayed recall. These findings reveal for the first time that subjective insomnia severity predicts objective effort mobilization in an easy memory task, suggesting that young poor sleepers recruit extra resources to cope with everyday cognitive challenges.     

The ability to self‐monitor cognitive performance during 60 h total sleep deprivation and following 2 nights recovery sleep

We aimed to investigate whether self‐monitoring of performance is altered during 60 h of total sleep deprivation, following 2 nights of recovery sleep, and by task difficulty and/or subjective sleepiness. Forty adults (22 females, aged 19–39 years) underwent a 5‐day protocol, with a well‐rested day, 66 h total sleep deprivation (last test session at 60 h), and 2 nights of 8 h recovery sleep. An arithmetic task (MATH) with three difficulty levels assessed working memory. The Psychomotor Vigilance Task assessed sustained attention. Arithmetic accuracy and Psychomotor Vigilance Task median reaction time measured objective performance. Subjective performance was measured with self‐reported accuracy and speed. Objective–subjective differences assessed self‐monitoring ability. The performance on both tasks declined during total sleep deprivation and improved following recovery. During total sleep deprivation, participants accurately self‐monitored performance on the Psychomotor Vigilance Task; however, they overestimated cognitive deficits on MATH, self‐reporting performance as worse than actually observed. Following recovery, participants overestimated the extent of performance improvement on the Psychomotor Vigilance Task. Task difficulty influenced self‐monitoring ability, with greater overestimation of performance deficits during total sleep deprivation as difficulty increased. Subjective sleepiness predicted subjective performance ratings at several time points, only for the Psychomotor Vigilance Task. The ability to self‐monitor performance was impaired during total sleep deprivation for working memory and after recovery sleep for the Psychomotor Vigilance Task, but was otherwise accurate. The development of self‐monitoring strategies, assessing both subjective perceptions of performance and subjective sleepiness, within operational contexts may help reduce the consequences of sleep‐related impairments.     

The relationship between a night's sleep and subsequent daytime functioning in older poor and good sleepers

Those suffering insomnia symptoms generally report daytime impairments. However, research has not assessed whether this relationship holds on a nightly basis, despite the strongly held belief that a night of poor sleep impairs mood and functioning the following day. The objective of this study was to test this relationship in a group of older poor sleepers with insomnia symptoms compared with good sleepers. This study utilized a within‐subjects design to investigate day‐to‐day subjective daytime functioning and its relation to the previous night's sleep. Seventeen older individuals (mean age: 67.5 years) were identified with a retrospective questionnaire and 2 weeks of sleep–wake diary to have poor sleep consistent with insomnia. Seventeen good sleepers (mean age: 67.8 years) were selected using the same measures. Participants reported their beliefs about sleep and daytime functioning on the Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS‐16). One week later they commenced a 14‐day period of sleep–wake diaries and concurrent responses to a modified Daytime Insomnia Symptom Scale (DISS). Results showed significant night‐to‐day covariation between sleep efficiency and daytime functioning for individuals with poor sleep (r = 0.34), but not for good sleepers (r = 0.08). Those poor sleepers who held this covariation belief most strongly were those who subsequently showed this night‐to‐day relationship the most strongly (r = 0.56). This was not true for good sleepers. For those suffering insomnia, these findings demonstrate their belief that a poor sleep is followed by an impaired daytime, consistent with their experience.     

Associations of domain‐specific physical activities with insomnia symptoms among 0.5 million Chinese adults

Previous studies have demonstrated the association between physical activity and sleep quality. However, there is little evidence regarding different domains of physical activity. This study aimed to examine the associations between domain‐specific physical activities and insomnia symptoms among Chinese men and women. Data of 452 024 Chinese adults aged 30–79 years from the China Kadoorie Biobank Study were analysed. Insomnia symptoms were assessed with self‐reported difficulties in initiating or maintaining sleep, early morning awakening, daytime dysfunction and any insomnia symptoms. Physical activity assessed by questionnaire consisted of four domains, including occupational, commuting‐related, household and leisure‐time activities. Gender‐specific multiple logistic regression models were employed to estimate independent associations of overall and domain‐specific physical activities with insomnia symptoms. Overall, 12.9% of men and 17.8% of women participants reported having insomnia symptoms. After adjustment for potential confounders, a moderate to high level of overall activity was associated with reduced risks of difficulties in initiating or maintaining sleep and daytime dysfunction in both sexes (odds ratios range: 0.87–0.94, P < 0.05). As to each domain of physical activity, similar associations were identified for occupational, household and leisure‐time activities in women but not men (odds ratios range: 0.84–0.94, P < 0.05). Commuting‐related activity, however, was associated with increased risks of difficulties in initiating or maintaining sleep and any insomnia symptoms in both sexes (odds ratios range: 1.07–1.17, P < 0.05). In conclusion, a moderate to high level of physical activity was associated with lower risks of insomnia symptoms among Chinese adults. However, such associations varied hugely in different domains of physical activity and with gender differences, which could help with better policy‐making and clinical practice.     

The subjective–objective mismatch in sleep perception among those with insomnia and sleep apnea

The diagnosis and management of insomnia relies primarily on clinical history. However, patient self‐report of sleep–wake times may not agree with objective measurements. We hypothesized that those with shallow or fragmented sleep would under‐report sleep quantity, and that this might account for some of the mismatch. We compared objective and subjective sleep–wake times for 277 patients who underwent diagnostic polysomnography. The group included those with insomnia symptoms (n = 92), obstructive sleep apnea (n = 66) or both (n = 119). Mismatch of wake duration was context dependent: all three groups overestimated sleep latency but underestimated wakefulness after sleep onset. The insomnia group underestimated total sleep time by a median of 81 min. However, contrary to our hypothesis, measures of fragmentation (N1, arousal index, sleep efficiency, etc.) did not correlate with the subjective sleep duration estimates. To unmask a potential relationship between sleep architecture and subjective duration, we tested three hypotheses: N1 is perceived as wake; sleep bouts under 10 min are perceived as wake; or N1 and N2 are perceived in a weighted fashion. None of these hypotheses exposed a match between subjective and objective sleep duration. We show only modest performance of a Naïve Bayes Classifier algorithm for predicting mismatch using clinical and polysomnographic variables. Subjective–objective mismatch is common in patients reporting insomnia symptoms. We conclude that mismatch was not attributable to commonly measured polysomnographic measures of fragmentation. Further insight is needed into the complex relationships between subjective perception of sleep and conventional, objective measurements.     

Self-reported cognition in older adults with insomnia: Associations with sleep and domain specific cognition

Poor subjective evaluation of cognition and sleep are associated with cognitive decline in older adults. Relationships among self-reported cognition, sleep, and cognitive domains remain unclear. We evaluated the interactive associations of objective cognition and subjective sleep with self-reported cognition in older adults with insomnia. Fifty-one older adults (M_age = 69.19, SD = 7.95) with insomnia completed 14 days of self-reported cognition ratings (0-very poor, 100-very good), sleep (total sleep time (TST), sleep onset latency (SOL), wake after sleep onset (WASO), sleep efficiency), and daily cognitive tasks: Letter series (reasoning), word list delayed recall (verbal memory), Symbol Digit Modalities Test (SDMT) (attention/processing speed), and number copy (processing speed). Multiple regressions for each cognitive task determined whether average objective cognition or sleep were independently/interactively associated with average self-reported cognition, controlling for age, education, and depression. The interaction between SDMT performance and TST was associated with self-reported cognition. Specifically, the relationship between scores and self-reported cognition was congruent in those with the shortest TST. Similarly, the interactions between SDMT and WASO, as well as sleep efficiency, were associated with self-reported. Specifically, the relationship between scores and self-reported cognition was congruent in those with longest and average WASO, as well as shortest and average sleep efficiency. The findings suggest, in an older adult population with insomnia, a congruent association exists between attention/processing speed and self-reported cognition in those with worse subjective sleep (shorter TST, longer WASO, and lower SE). Insomnia symptoms should be taken into consideration when examining the relationship between objective cognition and self-reported cognition.     

Working memory performance of older adults with insomnia

Older individuals suffering insomnia typically report declines in their cognitive performance beyond what they consider to be normal changes due to the aging process. Recent neuro‐imaging studies have demonstrated frontal lobe hypo‐activation among insomniac populations when compared with healthy, good sleepers. However, research is yet to confirm whether frontal lobe hypo‐activation translates into objective declines when performing tasks hypothesized to draw upon this brain region. This study aimed to investigate whether older insomnia sufferers demonstrate significantly impaired performance on a challenging working memory task when compared with age‐matched good sleepers. Forty‐nine older individuals (mean age = 69.43 years, SD = 4.83) suffering from sleep maintenance insomnia were compared with 49 age‐matched good sleepers. Cognitive performance was assessed using the Double Span Memory Task, a computer‐based working memory task that requires participants to indicate the names and/or spatial locations of increasingly longer sequences of visually presented objects. After controlling for general intelligence, the individuals suffering from insomnia did not perform differently when compared with the good sleepers on either the simpler or more cognitively demanding components of the task. Older individuals with insomnia did not display an observable impairment of working memory in this study relative to good sleepers. Despite the mixed results from previous research, this study adds weight to the absence of objective impairment in insomniacs, at least while performing short‐term demanding cognitive tasks.     

Insomnia and incident depression: role of objective sleep duration and natural history

Longitudinal studies that have examined the association of insomnia with incident depression using objective sleep measures are very limited. The aim of this study was to examine the predictive role of the severity of insomnia for incident depression in a general population sample using psychometric and polysomnographic data. From a random, general population sample of 1741 individuals of the Penn State Adult Cohort, 1137 adults without depression were followed up with a structured telephone interview after 7.5 years. All subjects completed a full medical evaluation, 1‐night polysomnogram and Multiphasic Minnesota Personality Inventory at baseline. The incidence of depression was 15%. Poor sleep (odds ratio = 1.5, P = 0.001) and insomnia (odds ratio = 1.9, P = 0.031) were significantly associated with incident depression. The odds of incident depression were highest (odds ratio = 2.2, P = 0.019) in insomnia with objective short sleep duration and independent of Multiphasic Minnesota Personality Inventory Ego Strength scores, an index of poor coping resources. The persistence of insomnia and worsening of poor sleep into insomnia significantly increased the odds of incident depression (odds ratios ranged from 1.8 to 6.3), whereas their full remission did not (odds ratio ranged from 1.2 to 1.8). Insomnia with short sleep duration is associated with incident depression independent of poor coping resources, whereas the association of insomnia with normal sleep duration with incident depression was mediated by poor coping resources. Persistence and worsening of poor sleep or insomnia, but not their full remission, are significant predictors of incident depression. These data suggest that there is a significant relationship between the severity of insomnia and incident depression.     

A rodent cage change insomnia model disrupts memory consolidation

Insomnia involves disruption of sleep initiation, maintenance and/or overall quality, and may interfere with cognition. Here, we evaluated memory impairment produced by rodent mild (acute) insomnia models. Insomnia models consisted of either single or repeated exposure to cages previously occupied (dirtied) by an unfamiliar rat for 5–7 days. Rats were trained in the Morris water maze to remember the platform location (acquisition), and were then exposed to: (a) 6 hr of undisturbed baseline; (b) dirty cage change‐induced insomnia (animal placed into a cage dirtied by another rat for 6 hr); or (c) double‐dirty cage change‐induced insomnia (animal placed into a cage dirtied by another rat for 3 hr, and then another dirty cage 3 hr later). The animal's memory for the platform location was then evaluated in a probe trial. Double‐dirty cage change‐induced insomnia significantly disrupted sleep, although the effects of dirty cage change‐induced insomnia were overall not significant. In the fourth hour of double‐dirty cage change‐induced insomnia (following the second cage change), sleep episode number and duration alterations indicated sleep fragmentation. Furthermore, power spectral analysis revealed diminished wake and, to a lesser extent, rapid eye movement theta power (indicated by trend difference) in the last 3 hr of exposure. Significant deficits were noted for measures of water maze performance following double‐dirty cage change‐induced insomnia, indicating impaired memory. In summary, one variant of the rodent insomnia model, double‐dirty cage change‐induced insomnia, disrupted sleep and attenuated memory consolidation, indicating this paradigm may be useful to evaluate the effects of hypnotics on memory consolidation.