Circadian rhythms and psychiatric profiles in young adults with unipolar depressive disorders.

Abnormalities in circadian rhythms have been reported in people with mood disorders, but these abnormalities are marked by considerable inter-individual variability. This study aimed to identify pathophysiological subgroups on the basis of circadian markers and evaluate how these subgroups relate to psychiatric profiles. Thirty-five young adults (18-31 years old) receiving clinical care for unipolar depressive disorders and 15 healthy controls took part to this study. The Hamilton Rating Scale for Depression and the Young Mania rating scale were used to evaluate the severity of mood symptoms in participants with depressive disorders. All participant underwent ambulatory sleep monitoring with actigraphy for about 12 days before attending a laboratory-based chronobiological assessment which included repeated salivary samples to determine dim light melatonin onset (DLMO) and continuous core body temperature (CBT) monitoring using an ingestible temperature sensor. Cluster analyses were conducted across all participants to identify subgroups with consistent circadian timing profiles based on DLMO and the nocturnal minima of CBT. Two clusters were identified: 'delayed' and 'conventional timing' circadian phase. Descriptive analyses showed that the delayed cluster was characterised by abnormal time relationships between circadian phase markers and the sleep-wake cycle. Importantly, individuals from the delayed cluster had worse depression severity (t(28) = -2.7, p = 0.011) and hypomanic symptoms (Z = -2.2, p = 0.041) than their peers with conventional circadian timing. These findings suggest that delayed and disorganised circadian rhythms may be linked to worse psychiatric profiles in young people with depressive disorders.

Ambulatory sleep-wake patterns and variability in young people with emerging mental disorders.

BACKGROUND: The nature of sleep-wake abnormalities in individuals with mental disorders remains unclear. The present study aimed to examine the differences in objective ambulatory measures of the sleep-wake and activity cycles across young people with anxiety, mood or psychotic disorders. METHODS: Participants underwent several days of actigraphy monitoring. We divided participants into 5 groups (control, anxiety disorder, unipolar depression, bipolar disorder, psychotic disorder) according to primary diagnosis. RESULTS: We enrolled 342 participants aged 12-35 years in our study: 41 healthy controls, 56 with anxiety disorder, 135 with unipolar depression, 80 with bipolar disorder and 30 with psychotic disorders. Compared with the control group, sleep onset tended to occur later in the anxiety, depression and bipolar groups; sleep offset occurred later in all primary diagnosis groups; the sleep period was longer in the anxiety, bipolar and psychosis groups; total sleep time was longer in the psychosis group; and sleep efficiency was lower in the depression group, with a similar tendency for the anxiety and bipolar groups. Sleep parameters were significantly more variable in patient subgroups than in controls. Cosinor analysis revealed delayed circadian activity profiles in the anxiety and bipolar groups and abnormal circadian curve in the psychosis group. LIMITATIONS: Although statistical analyses controlled for age, the sample included individuals from preadolescence to adulthood. Most participants from the primary diagnosis subgroups were taking psychotropic medications, and a large proportion had other comorbid mental disorders. CONCLUSION: Our findings suggest that delayed and disorganized sleep offset times are common in young patients with various mental disorders. However, other sleep-wake cycle disturbances appear to be more prominent in broad diagnostic categories.