Epidemiology of insomnia : prevalence, course, risk factors, and public health burden

This paper summarizes recent epidemiological evidence on insomnia, including its prevalence, incidence, and risk factors, as well as its course and consequences. There is now substantial evidence that insomnia is a significant public health problem. It is a highly prevalent condition, both as a symptom and a syndrome, and is often a persistent condition over time. Its persistence is associated with increased risk for mental (major depression), physical (hypertension), and occupational health problems (disability). Chronic insomnia also carries heavy economic burden, both in terms of direct healthcare costs and, more importantly, in terms of human resources loss due to the illness and lack of treatment. These findings have direct implications for community-based prevention and intervention programs and for future research including the need for: a) longitudinal, population-based studies aimed at evaluating whether we can prevent insomnia among at-risk individuals; b) clinical studies evaluating whether the morbidity associated with chronic insomnia is reversible; and c) prospective health economic evaluations of prevention programs using different dissemination technologies

Temporal Stability of the Ford Insomnia Response to Stress Test (FIRST)

Study objectives: The Ford Insomnia Response to Stress Test (FIRST) is a self-report tool that measures sleep reactivity (i.e., vulnerability to experience situational insomnia under stressful conditions). Sleep reactivity has been termed a "trait-like" vulnerability; however, evidence of its long-term stability is lacking. The main objective of the current psychometric study was to investigate the temporal stability of the FIRST over two 6-mo intervals in a population-based sample of adults with and without insomnia. The temporal stability of the FIRST was also compared with the temporal stability of other scales associated with insomnia (trait-anxiety, arousability). Methods: Participants included 1,122 adults (mean age = 49.9 y, standard deviation = 14.8; 38.8% male) presenting with an insomnia syndrome (n = 159), insomnia symptoms (n = 152), or good sleep (n = 811). Participants completed the FIRST, the State-Trait Anxiety Inventory (trait-anxiety), and the Arousal Predisposition Scale (arousability) on three different occasions: baseline and at 6- and 12-mo follow-up. Intraclass correlation coefficients (ICCs) were computed for all scales (baseline to 6 mo and 6 to 12 mo). Results: The FIRST yielded strong temporal stability from baseline to 6 mo among those with insomnia syndrome (ICC = 0.81), symptoms (ICC = 0.78), and good sleep (ICC = 0.81). Similar results were observed for 6 to 12 mo among those with insomnia syndrome (ICC = 0.74), insomnia symptoms (ICC = 0.82), and good sleep (ICC = 0.84). The stability of the FIRST was not comparable with the stability of trait-anxiety, but was somewhat comparable with the stability of arousability. Conclusions: Overall, the FIRST is a temporally reliable stable scale over 6-mo intervals. Future research is needed to corroborate the stability and trait-like measures of sleep reactivity with physiological, behavioural and personality measures

Monthly fluctuations of insomnia symptoms in a population-based sample

Study Objectives: To document the monthly changes in sleep/insomnia status over a 12-month period; to determine the optimal time intervals to reliably capture new incident cases and recurrent episodes of insomnia and the likelihood of its persistence over time. Design: Participants were 100 adults (mean age = 49.9 years; 66% women) randomly selected from a larger population-based sample enrolled in a longitudinal study of the natural history of insomnia. They completed 12 monthly telephone interviews assessing insomnia, use of sleep aids, stressful life events, and physical and mental health problems in the previous month. A total of 1,125 interviews of a potential 1,200 were completed. Based on data collected at each assessment, participants were classified into one of three subgroups: good sleepers, insomnia symptoms, and insomnia syndrome. Results: At baseline, 42 participants were classified as good sleepers, 34 met criteria for insomnia symptoms, and 24 for an insomnia syndrome. There were significant fluctuations of insomnia over time, with 66% of the participants changing sleep status at least once over the 12 monthly assessments (51.5% for good sleepers, 59.5% for insomnia syndrome, and 93.4% for insomnia symptoms). Changes of status were more frequent among individuals with insomnia symptoms at baseline (mean = 3.46, SD = 2.36) than among those initially classified as good sleepers (mean = 2.12, SD = 2.70). Among the subgroup with insomnia symptoms at baseline, 88.3% reported improved sleep (i.e., became good sleepers) at least once over the 12 monthly assessments compared to 27.7% whose sleep worsened (i.e., met criteria for an insomnia syndrome) during the same period. Among individuals classified as good sleepers at baseline, risks of developing insomnia symptoms and syndrome over the subsequent months were, respectively, 48.6% and 14.5%. Monthly assessment over an interval of 6 months was found most reliable to estimate incidence rates, while an interval of 3 months proved the most reliable for defining chronic insomnia. Conclusions: Monthly assessment of insomnia and sleep patterns revealed significant variability over the course of a 12-month period. These findings highlight the importance for future epidemiological studies of conducting repeated assessment at shorter than the typical yearly interval in order to reliably capture the natural course of insomnia over time

Temporal Evolution of the Magmatic System at Tungurahua Volcano, Ecuador, detected by geodetic observations

Changes in the pathway and timescale of magma ascent can be responsible for variations in eruptive style during long-lived eruptions, but are only documented at a small number of well-instrumented systems. Here we integrate PS-InSAR from high resolution TerraSAR-X radar imagery with continuous GPS data from 4 sites at Tungurahua volcano, Ecuador. Our results show long-term uplift between 2011-2014 associated with a continuously in ating prolate reservoir at a depth of 10 km beneath the summit. Comparisons with eruptive flux, taking compressibility into account, suggest that during this time period slightly over half the magma supplied to the system was erupted. The observations span three distinct phases of eruption and in 2012-2013, an increase in eruptive activity was accompanied by uplift on the volcano's western flank. Similar episodes have previously been observed during large Vulcanian eruptions and we attribute them to intrusions into an area of mechanical weakness. A localised patch of subsidence mid-way up the Tungurahua's western flank is co-located with a swarm of shallow long-period seismicity and may represent a potential site for a development of a lateral vent. This study demonstrates that satellite geodetic techniques are capable of characterising the geodetic signature of transitions in eruptive style during long-lived andesitic eruptions although the deformation is cm-scale of steep volcanic edi fices.NERC Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonic

Qualitative studies of insomnia : current state of knowledge in the field

Despite its high prevalence and burden, insomnia is often trivialized, under-diagnosed, and under-treated in practice. Little information is available on the subjective experience and perceived consequences of insomnia, help-seeking behaviors, and treatment preferences. The use of qualitative approaches (e.g., ethnography, phenomenology, grounded theory) may help gain a better understanding of this sleep disorder. The present paper summarizes the evidence derived from insomnia studies using a qualitative research methodology (e.g., focus group, semi-structured interviews). A systematic review of the literature was conducted using PsycINFO and Medline databases. The review yielded 22 studies and the quality of the methodology of each of them was evaluated systematically using the critical appraisal skills programme (CASP) appraisal tool. Selected articles possess at least a very good methodological rigor and they were categorized according to their main focus: “Experience of insomnia”, “Management of insomnia” and “Medicalization of insomnia”. The main findings indicate that: 1) insomnia is often experienced as a 24-h problem and is perceived to affect several domains of life, 2) a sense of frustration and misunderstanding is very common among insomnia patients, which is possibly due to a mismatch between patients' and health care professionals' perspectives on insomnia and its treatment, 3) health care professionals pay more attention to sleep hygiene education and medication therapies and less to the patient's subjective experience of insomnia, and 4) health care professionals are often unaware of non-pharmacological interventions other than sleep hygiene education. An important implication of these findings is the need to develop new clinical measures with a broader scope on insomnia and more targeted treatments that take into account the patient's experience of insomnia. Greater use of qualitative approaches in future research may produce novel and more contextualized information leading to a more comprehensive understanding of insomnia

The Reliability of the Factor Structure of the Pediatric Daytime Sleepiness Scale in both a Spanish-Colombian and French-Canadian Version

Daytime sleepiness is characterized by an increased likelihood of falling asleep and adversely impacts youth’s academic performance, behavior, and mood. The National Sleep Foundation Sur­vey (2006) found almost 50% of youth sleep 1 to 2 hours less than the recommended 9 hours per night and 60% report daytime sleepiness. The Pediatric Daytime Sleepiness Scale (PDSS; Drake et al., 2003) is a self-report questionnaire used to evaluate the likelihood of youth falling asleep in various everyday situations. The original PDSS was developed with an English-speaking American sample (Mage=11.8; SD=.6 years), and the measure was thought to assess a uni-dimensional construct: day­time sleepiness. The PDSS has previously been translated into a Spanish version for an Argentinean sample (Mage=13.3; SD=1.5 years)

Non-invasive intradialytic percutaneous perfusion monitoring: a view to the heart through the skin

IntroductionThe life-sustaining treatment of hemodialysis (HD) induces recurrent and cumulative systemic circulatory stress resulting in cardiovascular injury. These recurrent insults compound preexisting cardiovascular sequalae leading to the development of myocardial injury and resulting in extremely high morbidity/mortality. This is largely a consequence of challenged microcirculatory flow within the myocardium (evidenced by detailed imaging-based studies). Currently, monitoring during HD is performed at the macrovascular level. Non-invasive monitoring of organ perfusion would allow the detection and therapeutic amelioration of this pathophysiological response to HD. Non-invasive percutaneous perfusion monitoring of the skin (using photoplethysmography—PPG) has been shown to be predictive of HD-induced myocardial stunning (a consequence of segmental ischemia). In this study, we extended these observations to include a dynamic assessment of skin perfusion during HD compared with directly measured myocardial perfusion during dialysis and cardiac contractile function.MethodsWe evaluated the intradialytic microcirculatory response in 12 patients receiving conventional HD treatments using continuous percutaneous perfusion monitoring throughout HD. Cardiac echocardiography was performed prior to the initiation of HD, and again at peak-HD stress, to assess the development of regional wall motion abnormalities (RWMAs). Myocardial perfusion imaging was obtained at the same timepoints (pre-HD and peak-HD stress), utilizing intravenous administered contrast and a computerized tomography (CT)-based method. Intradialytic changes in pulse strength (derived from PPG) were compared with the development of HD-induced RWMAs (indicative of myocardial stunning) and changes in myocardial perfusion.ResultsWe found an association between the lowest pulse strength reduction (PPG) and the development of RWMAs (p = 0.03) and also with changes in global myocardial perfusion (CT) (p = 0.05). Ultrafiltration rate (mL/kg/hour) was a significant driver of HD-induced circulatory stress [(associated with the greatest pulse strength reduction (p = 0.01), a reduction in global myocardial perfusion (p = 0.001), and the development of RWMAs (p = 0.03)].DiscussionPercutaneous perfusion monitoring using PPG is a useful method of assessing intradialytic hemodynamic stability and HD-induced circulatory stress. The information generated at the microcirculatory level of the skin is reflective of direct measures of myocardial perfusion and the development of HD-induced myocardial stunning. This approach for the detection and management of HD-induced cardiac injury warrants additional evaluation