Your hair can reveal your circadian rhythm from a single sample

Key Findings

🌙 Cancer symptoms follow a daily pattern—and it's driven by disrupted clocks

• Patients with malignant tumors experience symptom fluctuations following the pattern "mild in the morning, stable by day, worsening in the evening, and severe at night"

• Disruptions in core circadian clock genes like BMAL1 and PER, combined with dysregulated cellular metabolism and immune responses, facilitate tumor growth and metastasis during nighttime hours

• These molecular changes contribute to symptom worsening through direct tumor invasion, neural infiltration, inflammatory processes, and abnormal melatonin secretion

⚽ Jet lag hits athletes harder when traveling east vs west

• Analysis of 89 studies found that eastward travel generally causes stronger circadian disruption and impairs aerobic capacity, coordination, and technical performance

• Westward travel often induces greater fatigue and more severely affects team-sport outcomes

• Travel effects included sleep disturbances (36 studies), fatigue (25 studies), decreased physical performance (18 studies), and mood changes (15 studies)

📱 Fitbit data reveals six key sleep dimensions in adolescents

• Researchers identified six distinct sleep health dimensions from 3,393 young adolescents using Fitbit data: irregularity, timing, social jetlag, duration, weekend oversleep, and continuity

• Greater sleep irregularity was linked to more mental health symptoms across all categories, while shorter sleep duration was associated with attention and psychotic symptoms one year later

• Sleep irregularity and duration emerged as the most important dimensions for predicting mental health outcomes in teens

🧠 Evening chronotype linked to worse psoriasis severity

• Among 213 adults with psoriasis, those with evening chronotypes had the highest disease severity scores (11.1 ± 6.3), far exceeding morning types (1.7 ± 1.1) and intermediate types (3.9 ± 1.2)

• Poor sleepers (sleep quality score > 5) had significantly higher psoriasis severity than good sleepers (10.3 ± 6.51 vs 2.3 ± 1.6)

• Evening chronotype showed the strongest independent association with disease severity, explaining 81% of the variance in psoriasis scores

🔬 Aging disrupts the anti-phase relationship between core clock genes

• In 24-month-old mice, the normal opposing rhythms between core clock genes BMAL1 and PER2 became disrupted, with senescence-associated genes showing pronounced daily oscillations

• Two distinct cell populations emerged that lacked normal BMAL1-PER2 relationships: one senescent-like and another profibrotic

• Aging increased transcriptional noise particularly in circadian-regulated pathways like RNA splicing, ribosome biogenesis, and metabolic signaling

💊 Circadian timing affects how stem cells respond to regenerative therapies

• Core circadian clock components directly control stem cell pathways through transcriptional regulation, shared enhancer architecture, and rhythmic protein modifications

• Disruption of circadian-stem cell crosstalk impairs tissue maintenance, reduces regenerative responses, and may promote tumor formation

• Stem cell populations across tissues show circadian oscillations that influence their self-renewal, proliferation, and differentiation capabilities