Sleep in later life: a population-based approach

This dissertation includes six epidemiological studies of sleep in a normal elderly population. The research was conducted within the setting of the Rotterdam Study, a large prospective cohort study of community-dwelling inhabitants of a district of Rotterdam, aged 55 and over. A total of 1076 persons participated in an additional sleep study, in which their sleep was ‘measured’ with a sleep diary and with actigraphy, a method that infers sleep and wakefulness from the presence or absence of arm movement. The following topics are addressed in this dissertation: gender differences in sleep duration and sleep quality, disagreement between diary and actigraphy measures of sleep parameters, the relationship between sleep duration and cardiovascular disease and risk factors (obesity, hypertension and cholesterol levels) and sleep in depression and anxiety disorders. One of the remarkable conclusions is that women report shorter and poorer sleep in their diaries, but when measured with actigraphy, women show longer and less fragmented sleep than men. Furthermore, both persons who habitually sleep less than 6 hours per night and persons who tend to sleep more than 8 hours per night, have a higher risk of obesity. Also, these groups had more depressive and anxiety disorders. All studies showed a considerable disagreement between measurement methods. This implies that sleep remains a mysterious phenomenon that cannot easily be precisely measured in the home situation. Longitudinal r! esearch is needed to further elucidate the effects of (lack of) sleep on physical and mental health

Chronotype and depressive symptoms in students: An investigation of possible mechanisms

Individuals with an evening chronotype are at increased risk of experiencing emotional problems, including depressive symptoms. However, the mechanisms underlying these associations remain unclear. The present study aimed to determine whether poor sleep quality, substance use and cognitive emotion regulation difficulties – which have been implicated in the etiology of depression – mediate the relationship between chronotype and depressive symptoms in a student sample, which was assessed cross-sectionally and after 1 year. A total of 742 Dutch students (75% women, mean age 21.4 ± 2.9 years) completed the Quick Inventory of Depressive Symptomatology, the Morningness-Eveningness Questionnaire, the Pittsburgh Sleep Quality Index, a questionnaire assessing alcohol, caffeine, tobacco and cannabis use, the Cognitive Emotion Regulation Questionnaire and the Behavioral Inhibition/Activation Scale. A subsample (n = 115) was assessed 1 year later with the same questionnaires. Cross-sectional analyses showed that evening chronotype was associated with more depressive symptoms, adjusted for age and gender (β = −0.082, p = 0.028). The relationship between eveningness and depressive symptoms was mediated by sleep quality, alcohol consumption and the cognitive emotion regulation strategies of self-blame and positive reappraisal. In longitudinal analyses, eveningness at baseline predicted more depressive symptoms at follow-up, adjusted for age and gender (β = −0.29, p = 0.002); after additional adjustment for baseline depressive symptoms, chronotype remained a significant predictor of depressive symptoms at T2 (β = −0.16, t = −2.01, p = 0.047). Only poor sleep quality at follow-up was a significant mediator of this relationship. Even though the effect is small in terms of explained variance, eveningness is related to depressive symptoms and this relationship is mediated by poor sleep quality, also in a prospective design. Self-blame and reduced positive reappraisal are correlated with eveningness. Further research is needed to assess the efficacy of chronotherapeutic interventions for the prevention of depression, in addition to sleep education and cognitive approaches.Article / Letter to editorInstituut Psychologi

Sleep quality in students: associations with psychological and lifestyle factors

Disturbed sleep is prevalent in adult populations and has been associated with negative health outcomes. This cross-sectional study assessed how psychological and lifestyle factors relate to subjective sleep quality in university students. In a large (N = 1114) sample of Dutch university students we assessed chronotype (Morningness-Eveningness Questionnaire), depressive symptoms (Quick Inventory of Depressive Symptoms), cognitive emotion regulation styles (Cognitive Emotion Regulation Questionnaire), and substance use (caffeine, alcohol, smoking, cannabis), and analysed whether these factors were related to subjective sleep quality (Pittsburgh Sleep Quality Index). The sample was predominantly (77.8%) female, mean age 21.1 (SD = 2.9) years, and 42.8% had clinically significant poor subjective sleep quality. More eveningness (B = -.05, p = .001), more depressive symptoms (B = .31, p = .001), less use of the emotion regulation strategy 'putting into perspective' (B = -.06, p = .02) and smoking (B = .53, p = .02) were independently associated with poorer subjective sleep quality. More eveningness, more depressive symptoms, less use of the emotion regulation style 'putting into perspective' and smoking were independently associated with poorer subjective sleep quality in a large sample of Dutch university students.Stress and Psychopatholog

Evening use of caffeine moderates the relationship between caffeine consumption and subjective sleep quality in students

Caffeine is often used to reduce sleepiness; however, research suggests that it can also cause poor sleep quality. The timing of caffeine use, amongst other factors, is likely to be important for the effects it has on sleep quality. In addition, individual differences exist in the effect of caffeine on sleep quality. This cross‐sectional study investigated the influence of the timing of caffeine consumption on and a possible moderating role of chronotype in the relationship between caffeine consumption and sleep quality in 880 students (74.9% female, mean age 21.3 years, SD = 3.1). Respondents filled in online questionnaires about chronotype (the Morningness–Eveningness Questionnaire), sleep quality (the Pittsburgh Sleep Quality Index) and caffeine consumption. Mean caffeine consumption was 624 mg per week, and 80.2% of the sample drank caffeine after 18:00 hours. Regression analyses demonstrated that higher total caffeine consumption was only related to poorer sleep quality for people who did not drink caffeine in the evening (β = 0.209, p = .006). We did not find a relationship between caffeine and sleep quality in people who drank caffeine in the evening (β = −0.053, p = .160). Furthermore, we found no evidence for a moderating role of chronotype in the relationship between caffeine consumption and sleep quality. We concluded that a self‐regulating mechanism is likely to play a role, suggesting that students who know that caffeine negatively affects their sleep quality do not drink it in the evening. Caffeine sensitivity and the speed of caffeine metabolism may be confounding variables in our study. FSW - Self-regulation models for health behavior and psychopathology - ou

Evening use of caffeine moderates the relationship between caffeine consumption and subjective sleep quality in students

Caffeine is often used to reduce sleepiness; however, research suggests that it can also cause poor sleep quality. The timing of caffeine use, amongst other factors, is likely to be important for the effects it has on sleep quality. In addition, individual differences exist in the effect of caffeine on sleep quality. This cross‐sectional study investigated the influence of the timing of caffeine consumption on and a possible moderating role of chronotype in the relationship between caffeine consumption and sleep quality in 880 students (74.9% female, mean age 21.3 years, SD = 3.1). Respondents filled in online questionnaires about chronotype (the Morningness–Eveningness Questionnaire), sleep quality (the Pittsburgh Sleep Quality Index) and caffeine consumption. Mean caffeine consumption was 624 mg per week, and 80.2% of the sample drank caffeine after 18:00 hours. Regression analyses demonstrated that higher total caffeine consumption was only related to poorer sleep quality for people who did not drink caffeine in the evening (β = 0.209, p = .006). We did not find a relationship between caffeine and sleep quality in people who drank caffeine in the evening (β = −0.053, p = .160). Furthermore, we found no evidence for a moderating role of chronotype in the relationship between caffeine consumption and sleep quality. We concluded that a self‐regulating mechanism is likely to play a role, suggesting that students who know that caffeine negatively affects their sleep quality do not drink it in the evening. Caffeine sensitivity and the speed of caffeine metabolism may be confounding variables in our study

Nieuwe gebruiksvormen van voormalige agrarische bedrijfsgebouwen in de Gelderse Vallei

In zes studiegebieden in de Gelderse Vallei is de aard en omvang van niet (meer) agrarische bebouwing in het buitengebied vastgesteld. Deze bebouwing, die in meer dan 90% van de gevallen alleen een woonfunctie heeft, overtreft het aantal gebouwen van actieve agrariërs. Er is ook een belevingsonderzoek uitgevoerd

De waargenomen kwaliteit van landschapsveranderingen : theoretisch en experimenteel onderzoek naar de mogelijkheden van een model voor het verklaren en voorspellen van de waargenomen kwaliteit van natuurontwikkelingsmaatregelen

Met behulp van computermodellen is getracht meer inzicht te krijgen in mogelijke oorzaken in de waargenomen kwaliteit van natuurontwikkelingsmaatregelen. de gebruiksdoelen en de presentatie van maatregelen als een veranderingsplan

Validation of an activity monitor for children who are partly or completely wheelchair-dependent

Background: Children who are wheelchair-dependent are at risk for developing unfavorable physical behavior; therefore, assessment, monitoring and efforts to improve physical behavior should start early in life. VitaMove is an accelerometer-based activity monitor and can be used to detect and distinguish different categories of physical behavior, including activities performed in a wheelchair and activities using the legs. The purpose of this study was to assess the validity of the VitaMove activity monitor to quantify physical behavior in children who are partly or completely wheelchair-dependent. Methods: Twelve children with spina bifida (SB) or cerebral palsy (CP) (mean age, 14 ±4 years) performed a series of wheelchair activities (wheelchair protocol) and, if possible, activities using their legs (n = 5, leg protocol). Activities were performed at their own home or school. In children who were completely wheelchair-dependent, VitaMove monitoring consisted of one accelerometer-based recorder attached to the sternum and one to each wrist. For children who were partly ambulatory, an additional recorder was attached to each thigh. Using video-recordings as a reference, primary the total duration of active behavior, including wheeled activity and leg activity, and secondary agreement, sensitivity and specificity scores were determined. Results: Detection of active behaviour with the VitaMove activity monitor showed absolute percentage errors of 6% for the wheelchair protocol and 10% for the leg protocol. For the wheelchair protocol, the mean agreement was 84%, sensitivity was 80% and specificity was 85%. For the leg protocol, the mean agreement was 83%, sensitivity was 78% and specificity was 90%. Validity scores were lower in severely affected children with CP. Conclusions: The VitaMove activity monitor is a valid device to quantify physical behavior in children who are partly or completely wheelchair-dependent, except for severely affected children and for bicycling