Multilevel modeling of chronotype and weekdays versus weekends to predict nonrestorative sleep

Circadian preference and sleep quality in healthy controls and psychiatric inpatients with major depressive disorder - An actigraphy study incorporating morning and evening mood assessments

Major depressive disorder (MDD) is frequently accompanied by sleep disturbance. Regarding diurnal preference (chronotype), sleep problems and low mood have been associated with evening orientation. Considering diurnal preference, we investigated subjective restorative value of sleep and actigraphy sleep parameters together with mood assessments twice a day, i.e. in the morning and evening, during weekdays and weekends in MDD psychiatric inpatients and healthy controls (HCs). The restorative value of sleep was higher during the weekend in HC, and bedtimes and risetimes were delayed during the weekend compared to weekdays in HC and MDD. Morning mood affected subjective sleep ratings in both groups, while association with symptom severity (BDI) in MDD remained insignificant. In HC, better evening mood was associated with later bedtimes. Regarding the chronotype in HC, evening orientation was associated with relatively low restorative value of sleep during weekdays, and morning orientation was associated with relatively higher actigraphy sleep efficiency during weekdays compared to weekend. In MDD, an association of evening orientation with later rise times could be observed, while no chronotype dependent effect emerged regarding the restorative value of sleep or sleep efficiency. Our results emphasize that research on sleep in MDD should incorporate weekdays as well as weekends, chronotype assessment, and measures of morning and evening mood, as these can be associated with ratings of the subjective restorative value of sleep (i.e. in our study, better morning mood was associated with higher restorative values), but also with behavioral sleep parameters (i.e. in our study, more positive evening mood was associated with later bedtimes). Potentially, the restorative value of sleep in MDD evening types can be improved by maintaining a regular sleep schedule, which needs to be investigated in an experimental design.

Associations between chronotype, social jetlag, and weekday sleep in women with irritable bowel syndrome

Sleep deficiency is well-documented in individuals with irritable bowel syndrome (IBS). Sleep deficiency includes poor sleep quality and an inadequate amount of sleep, and is a modifiable risk factor for IBS symptom exacerbations. Prior studies in other populations have identified chronotype and social jetlag (SJL) as important determinants of sleep outcomes. However, chronotype and SJL have not been examined in women with IBS. We used multiple linear regression analyses to determine whether chronotype and SJL are associated with sleep outcomes during weekdays among women with IBS predominant constipation (IBS-C), IBS with predominant diarrhea (IBS-D), and healthy control (HC) women. This sample included 62 women with IBS (IBS-C = 29, IBS-D = 33) and 58 HC women who completed a 28-day daily diary from two study cohorts. The average age of the participants was 30.1 (SD 7.2) years. Chronotype was estimated from daily diary data with the average mid-sleep time on weekends (MSW^we). SJL was calculated by subtracting the average mid-sleep time on weekdays from MSW^we. Sleep outcomes included diary assessments of sleep quality, sleep need met, and restorative sleep during weekdays. In HCs, later chronotype was predictive of lower sleep quality (β = -0.19, p < .01), a perception of sleep need not met (β = -0.17, p < .001), and a less restorative sleep during weekdays (β = -0.15, p = .073), whereas SJL was not associated with sleep outcomes. Similar to HCs, earlier chronotypes in women with IBS-C reported better sleep quality and more sufficient sleep need met and restorative sleep during weekdays than later chronotypes (all p > .05). Compared to HCs, the relationships of chronotype with weekday sleep outcomes in the women with IBS-D were in the opposite directions (all p < .05). This exploratory study suggests that chronotype expression may reflect the temporal associations of sleep outcomes within IBS bowel pattern predominance subgroups, particularly sleep quality and sleep need met. Additional investigations are warranted to examine whether specific temporal attributes of symptoms and/or symptom severity associated with IBS subgroups contribute to chronotype expression.

Daily associations between sleep and physical activity: A systematic review and meta-analysis

The day-to-day variations of sleep and physical activity are associated with various health outcomes in adults, and previous studies suggested a bidirectional association between these behaviors. The daily associations between sleep and physical activity have been examined in observational or interventional contexts. The primary goal of the current systematic review and meta-analysis was to summarize existing evidence about daily associations between sleep and physical activity outcomes at inter- and intra-individual level in adults. A systematic search of records in eight databases from inception to July 2019 identified 33 peer-reviewed empirical publications that examined daily sleep-physical activity association in adults. The qualitative and quantitative analyses of included studies did not support a bidirectional daily association between sleep outcomes and physical activity. Multilevel meta-analyses showed that three sleep parameters were associated with physical activity the following day: sleep quality, sleep efficiency, and wake after sleep onset. However, the associations were small, and varied in terms of direction and level of variability (e.g., inter- or intra-individual). Daytime physical activity was associated with lower total sleep time the following night at an inter-person level with a small effect size. From a clinical perspective, care providers should monitor the effects of better sleep promotion on physical activity behaviors in their patients. Future studies should examine sleep and physical activity during a longer period and perform additional sophisticated statistical analyses. SYSTEMATIC REVIEW REGISTRATION: https://osf.io/w6uy5/.

The SSRI citalopram increases the sensitivity of the human circadian system to light in an acute dose

RATIONALE

Disturbances of the circadian system are common in depression. Though they typically subside when depression is treated with antidepressants, the mechanism by which this occurs is unknown. Despite being the most commonly prescribed class of antidepressants, the effect of selective serotonin reuptake inhibitors (SSRIs) on the human circadian clock is not well understood.

OBJECTIVE

To examine the effect of the SSRI citalopram (30 mg) on the sensitivity of the human circadian system to light.

METHODS

This study used a double-blind, placebo-controlled, within-subjects, crossover design. Participants completed two melatonin suppression assessments in room level light (~ 100 lx), taking either a single dose of citalopram 30 mg or a placebo at the beginning of each light exposure. Melatonin suppression was calculated by comparing placebo and citalopram light exposure conditions to a dim light baseline.

RESULTS

A 47% increase in melatonin suppression was observed after administration of an acute dose of citalopram, with all participants showing more suppression after citalopram administration (large effect, d = 1.54). Further, melatonin onset occurred later under normal room light with citalopram compared to placebo.

CONCLUSIONS

Increased sensitivity of the circadian system to light could assist in explaining some of the inter-individual variability in antidepressant treatment responses, as it is likely to assist in recovery in some patients, while causing further disruption for others.