Depression is heterogeneous in severity and symptom dynamics. The present study examined whether distinct within-year trajectories of depression symptoms exist and how they relate to self-care behaviours. In this longitudinal study, 4801 individuals (Mage = 35.6 years, 18-81 years, 72.7% women) completed monthly assessments of depression (PHQ-9; 30,740 observations) and quarterly assessments on self-care behaviours (sleep and rhythm, leisure and activity, nutritional aids, social activities, and substance use) (9296 observations) between July 2020-June 2022. Growth mixture modelling identified five depression trajectories: three stable classes – Mild (n = 1419, 29.6%), Moderate (n = 1463, 30.5%), Severe (n = 1587, 33.1%) – and two seasonal classes – Winter-worsening (n = 215, 4.5%) and Summer-worsening (n = 117, 2.4%). Generalized additive mixed effect models showed marked within-year changes in self-care among the seasonal classes. The Summer-worsening class declined in daily rhythm, sleep sufficiency, and enjoyment of leisure activities during summer. The Winter-worsening class showed milder declines but during winter, and additionally included reduced physical exercise. Self-care behaviours remained relatively stable across the year in the Stable classes, with especially clear between-class differences in sleep sufficiency, daily rhythm, exercise, and enjoyment of leisure activities. Within-person analyses showed that months with higher-than-usual depression coincided with poorer-than-usual daily rhythm, hygiene, sleep sufficiency, and enjoyment of leisure activities. These patterns point to pragmatic, time-sensitive targets, where promoting stable routines in areas of sleep, leisure, and physical activities ahead of peaks may help prevent symptom escalation. For individuals with persistently severe depression, core self-care behaviours (sleep, daily rhythm, social engagement and enjoyment of leisure activities) remain priority treatment targets year-round.

Sleep loss and low-grade inflammation are common stressors that affect behaviour and recovery needs. To examine their separate and combined effects on motivation for everyday behaviours, we developed a two-hit experimental model. Participants (N = 56, 31 women) completed three experimental visits: sleep saturation (two nights, 9 h in bed/night); sleep-restriction (two nights, 4 h in bed/night); and an immune challenge (~24 h post COVID-19 vaccination) combined with either sleep saturation (n = 26) or restriction (n = 30). Motivation for everyday behaviours and sleepiness were rated, and blood samples were collected. Both sleep restriction and vaccination increased motivation for sleep-related behaviours and reduced motivation for physical and social activity, with sleep restriction having broader effects. These changes were associated with inflammation and sleepiness. Vaccination increased thirst, while sleep restriction reduced it, but neither affected hunger or food preferences. Sleep restriction amplified the inflammatory response to vaccination. For motivation, the stressors combined caused larger changes than either alone for some outcomes, without amplifying one another. These findings support that different stressors reallocate motivation towards rest and sleep-supporting behaviours over physical and social activity, likely to drive behaviours that support homeostasis after allostatic challenges. As these stressors often co-occur, this adaptive response can meaningfully shape daily functioning. Future work may determine when this functional response becomes maladaptive.

Sleep disturbances and inflammation are interconnected through shared regulatory mechanisms and are both implicated in age-related diseases. However, their connection at the level of brain-specific inflammation remains underexamined in humans. This study investigated whether specific dimensions of sleep are associated with microglial density, as measured by translocator protein (TSPO) levels, a biomarker of neuroinflammation. TSPO levels were measured using a single [¹¹C]PBR28 positron emission tomography (PET) scan in 39 healthy adults aged 50–81 years (M_age = 66.7, SD = 8.9; 19 females, 20 males). Sleep dimensions were assessed using the Karolinska Sleep Questionnaire on three occasions over five years, twice before and once around the time of PET imaging. Shorter sleep, more frequent napping, daytime fatigue, and sleep insufficiency were associated with higher TSPO levels in the middle frontal cortex (MFC). Conversely, longer sleep was associated with higher TSPO levels in the hippocampus and putamen. Exploratory factor analysis and bootstrapping confirmed a negative association between a factor representing shorter sleep and MFC TSPO levels. Additionally, a greater deviation from optimal sleep duration over the five years, in either direction from eight hours, was associated with higher current TSPO levels in all but one examined brain regions. Peripheral C-reactive protein levels did not significantly correlate with the sleep variables or TSPO levels in any of the brain regions. Analyses were adjusted for age and sex. These findings suggest that insufficient and prolonged sleep durations are associated with elevated microglial density in frontostriatal and limbic systems, respectively, among healthy middle-aged and older adults, without any associations with peripheral inflammation. Further longitudinal studies are needed to clarify directionality and whether changes in sleep duration over time may serve as early indicators of brain health.

Chronotype, the individual propensity towards morningness or eveningness, is a transdiagnostic factor implicated in mental health. How chronotype covaries with distinct psychiatric symptoms across the adult lifespan remains underinvestigated. In this cross-sectional study, 428 participants (18–70 years, evenly distributed across five age groups; 282 women, 143 men, other gender identity) completed the Reduced Morningness-Eveningness Questionnaire to approximate chronotype, and 11 validated scales assessing common psychiatric symptoms. Regression analyses and generalized additive models (GAMs) were used to examine linear and nonlinear relationships between chronotype, age, and psychiatric symptoms. Eveningness was associated with (in decreasing order of strength): emotion dysregulation, attention-deficit/hyperactivity disorder (ADHD), depression, autism, emotional instability, generalized anxiety, social anxiety, and impulsivity symptoms. Morningness was associated with mania symptoms. No significant associations were found between chronotype and delusional ideation or obsessive compulsive disorder (OCD) symptoms. Psychiatric symptom severity was generally lower with increasing age, particularly for emotional instability, emotion dysregulation, and ADHD. Nonetheless, certain symptoms persisted across age in eveningness (depression, generalized anxiety, OCD, ADHD), while other symptoms were lower (mania) or higher (social anxiety and delusional ideation) with eveningness at older ages. Except for mania symptoms, morningness in older age was not associated with higher symptom burden than eveningness for any other psychiatric domains. These results are consistent with the idea that morningness may be protective, being associated with lower psychiatric symptom levels in both younger and older age groups. In contrast, eveningness was associated with higher levels of autism, social anxiety and delusional ideation symptoms in older age.

Arousal is a central component of many emotional symptoms and can contribute to insomnia. Here we assessed how the timing and fluctuating nature of arousal-related symptoms over the course of the day relate to insomnia symptom severity. In this study, 361 participants (M age = 31.9 years, 282 women, 77 men, 2 non-binary individuals) completed the Insomnia Severity Index to assess severity of insomnia symptoms, followed by repeated ratings of anxiety or nervousness, stress, sleepiness, and feeling down via their mobile phone between ~08:00 hours and 00:00 hours across 1 day. Measures of dynamics included: mean levels across the day; variation (standard deviation); instability (mean squared successive differences); and resistance to change/inertia (first-order autocorrelation). Time-of-day patterns were modelled using generalized additive mixed effects models. Insomnia symptom severity (mean Insomnia Severity Index = 9.1, SD = 5.2, range 0–25) was associated with higher mean levels of all arousal-related symptoms, and increased instability and variation throughout the day in anxiety or nervousness, stress, and feeling down. Resistance to change (inertia) was not associated with insomnia symptom severity. Generalized additive mixed effects analyses showed that while individuals with more severe insomnia symptoms had elevated symptoms across the entire day, they were especially more anxious or nervous and sleepy in the early morning (~08:00 hours), anxious or nervous, stressed and sleepy in the late afternoon/early evening (~16:00 hours–21:00 hours), and anxious or nervous and stressed in the late evening (~22:00 hours). Remarkably, higher arousal occurred in the presence of high subjective sleepiness. Together these results indicate that insomnia symptom severity is associated with problems with daytime and evening arousal regulation.

Study objectives: Short and long sleep duration as well as poor sleep quality have been linked to higher prevalence of metabolic disorders. However, it is still unclear how diverse sleep variables relate to different metabolic pathways. This study examines how different features of sleep health relate to serum metabolites.

Methods: The study used data from 197 healthy individuals aged 20–79 (Females n = 103) from the IronAge study performed at Karolinska Institutet in Sweden. Sleep variables were assessed with the Karolinska Sleep Questionnaire, where the following variables were computed: sleep duration, sleep debt, midpoint, social jetlag (i.e., the discrepancy between midpoint on free and workdays), napping frequency and sleep quality. Morning fasting blood samples were collected and ¹H NMR spectroscopy was utilized for metabolomic analysis. The metabolites were categorized according to their major metabolic pathways: amino acid, lipid, carbohydrate, energy and gut microbiota. Linear regressions were performed to examine the relationship between each sleep variable and metabolite.

Results: Sleep duration, midpoint of sleep on free days, social jetlag and chronotype associated with eight metabolites at a significance level of p<0.01. Notably, midpoint associated with most metabolites spanning multiple pathways. A later midpoint was associated with higher levels of metabolites in the lipid pathway, and lower levels in the amino acid and energy pathway.

Conclusion: These observations indicate that sleep timing features, midpoint and social jetlag, have a stronger relationship with morning metabolism than other sleep health dimensions. Following replication in larger samples, these complex relationships may hold potential for health promotion.

While altered motivation is central in sickness behavior, previous research has mainly focused on motivation for rewards, rather than motivational changes in a broader perspective. In a larger study following a randomized within-subject placebo-controlled crossover design, we investigated the effects of systemic inflammatory activation on self-rated motivation in 21 healthy participants, using an intravenous injection of 2.0 ng/kg body weight lipopolysaccharide (LPS) compared to an intravenous injection of saline (placebo). Self-rated motivation was measured before, 3 h, and 7.5 h post-injection using the Motivation Scale of Sickness (MOSSick), a newly developed tool designed to assess motivational changes during sickness. It contains 26 items covering motivational drives related to hunger, thirst, and food preferences; resting, physical, and social activities; care seeking; and utilization of resources (i.e., willingness to ‘pay’ and ‘walk’) to be able to rest or to be healthy at once. At the peak of the sickness response (3 h post-LPS injection), there was an increased motivation to seek care, rest, and sleep, as compared to placebo, while motivation to partake in physical and social activities decreased. Several of these effects remained at 7.5 h post-injection. When in the LPS condition, participants were also willing to pay more money to rest and to be healthy compared to when in the placebo condition. Hunger increased over time in both conditions, but less after LPS administration. During the peak of the sickness response, higher sickness ratings were weakly associated with lower motivation for social activities and higher motivation for resting and sleeping. No further association was found between motivational drives and sickness ratings or other sickness measures, i.e. concentrations of cytokines and tympanic temperature, although sample size was limited for these analyses. These findings illustrate that motivational changes during acute sickness are not restricted to a general decrease in motivation. Instead, sick individuals are more motivated to take part in behaviors that enable energy preservation, care, and recovery, compared to when healthy.

Introduction: Vaccination-related conspiracy ideation is related to reduced compliance with public health advice globally. Such beliefs have previously been linked to the delusion-proneness trait. However, it is not known how this extends to getting vaccinated.

Methods: Here, we examined how delusion-proneness, as assessed by Peters et al. Delusions Inventory (PDI), is associated with COVID-19 vaccination in a sample of 273 subjects. We also examined whether delusion-proneness predicted the time to get vaccinated, after the vaccine became available.

Results: Unvaccinated subjects were more delusion-prone than vaccinated subjects (W=2225.5, p<0.001, effect-size=0.27). Among vaccinated subjects, higher delusion-proneness was related to longer time to get vaccinated (r_s=0.27, p<0.001). These effects remained after adjusting for anxiety, ADHD, and ASD (Autism Spectrum Disorder) traits as well as for psychiatric diagnoses and sex. Path analyses indicated that the effect of delusion-proneness on vaccination rate was strongly mediated through COVID-19 conspiracy ideation, suggesting that delusion prone individuals first develop specific delusion-like ideas regarding vaccination, which then delays vaccination. An exploratory analysis of written text by subjects instructed to explain why they had vaccinated or not, revealed a difference in reasoning between the groups. Unvaccinated individuals were primarily motivated by concerns about personal safety and potential side effects, while vaccinated individuals stated a desire to protect themselves and others as the primary reasons to get vaccinated.

Discussion: Our results suggest that delusion-proneness is a key factor for attaining conspiracy beliefs, at least in relation to COVID-19 pandemic, and associated with lower vaccination rates as well as longer time to get vaccinated.

Anxiety symptoms vary moment-to-moment within a day. One factor that may influence these variations is chronotype. Evening chronotypes prefer to engage in activities (e.g., sleep, physical and social activity) later in the day, and evening chronotype is implicated in psychopathology, including anxiety-related disorders. However, it is unknown whether chronotype influences diurnal variation in anxiety symptoms and whether these effects are amplified in individuals with a probable anxiety-related disorder. We examined the diurnal variation in anxiety symptoms and daily activities in morning and evening chronotypes with and without probable generalized anxiety disorder (GAD) or obsessive-compulsive disorder (OCD) in a community sample of adults (N = 410). Evening chronotypes reported higher anxiety symptoms, particularly in the evening hours, and lower engagement in daily activities, predominantly in the morning hours. Evening chronotypes with probable GAD or OCD reported worse anxiety symptoms in the evening. Our findings indicate that anxiety symptoms and engagement in daily activities fluctuate considerably across the day, and these patterns differ depending on chronotype. Evening chronotypes have more anxiety symptoms in the evening, despite preferring this time of day. Personalized treatment approaches that consider chronotype and target certain times of day may be efficient in alleviating peaks in anxiety symptoms.

The current studies examined the impact of insufficient sleep and sleepiness on the subjective experience of age. Study 1, a cross-sectional study of 429 participants (282 females (66%), 144 males, 3 other gender; age range 18-70), showed that for each additional day of insufficient sleep in the last 30 days, subjective age increased by 0.23 years. Study 2, an experimental crossover sleep restriction study (n = 186; 102 females (55%), 84 males; age range 18-46), showed that two nights of sleep restriction (4 h in bed per night) made people feel 4.44 years older compared to sleep saturation (9 h in bed per night). Additionally, moving from feeling extremely alert (Karolinska Sleepiness Scale (KSS) score of 1) to feeling extremely sleepy (KSS score of 9) was associated with feeling 10 years older in both studies. These findings provide compelling support for insufficient sleep and sleepiness to exert a substantial influence on how old we feel, and that safeguarding sleep is probably a key factor in feeling young.