Researchers at the University of Sydney propose that certain sleep-related traits may indicate a new type of depression they call “circadian depression.” This concept emerges from a study suggesting that individuals displaying at least three of six specific traits such as late sleeping, social jet lag, and seasonal mood swings could represent a specific subgroup of depression.
The findings, derived from a cohort of over 11,000 participants, revealed that approximately 25% exhibited these traits. However, the researchers noted that the data collected were self-reported, lacking confirmation through wearable devices or melatonin levels. Those identified with circadian depression exhibited earlier onset and more severe symptoms and had heightened genetic risks for conditions such as ADHD, bipolar disorder, and insulin resistance.
Emiliana Tonini, the study’s first author, emphasized that these individuals suffer from a disrupted or dysregulated circadian rhythm, which seems to play a critical role in their depression. Co-senior author Jacob Crouse noted the heterogeneity of depression, stating that many who recognized their experiences in the study reported previous treatments had been ineffective for them.
While those in this new subgroup found that antidepressants tended to be less effective, the researchers cautioned that this could be due to various individual factors, including possibly having bipolar disorder. Further research is necessary before formally recognizing this new subtype of depression, as there are concerns that these characteristics might align with those of individuals suffering more severely.
Studies indicate that while disrupted circadian rhythms are widely prevalent among those with depression, causality remains difficult to determine; some findings suggest that late bedtimes correlate with higher depression rates, but it’s unclear whether this behavior results from the depression or contributes to it. Notably, other studies have linked earlier sleep patterns with lower depression risk.
As the researchers investigate treatment options, they highlight potential therapies that focus on regulating circadian rhythms, such as bright light therapy, which have shown promise in some cases. However, evidence supporting the use of melatonin remains inconsistent. The Australian research team anticipates further studies to better understand the impact of sleep patterns on depression and explore the efficacy of melatonin as a treatment for young adults fitting the circadian depression profile.
