Melatonin Mediates Telomere Stability by Buffering Epigenetic Entropy Driven by Circadian Disruption

Hypothesis

Circadian disruption increases epigenetic entropy at subtelomeric regions, accelerating telomere shortening independent of replication count. Melatonin, whose secretion is suppressed by light exposure, reduces this epigenetic noise and thereby preserves telomere length.

Mechanistic Rationale

• Telomere attrition is traditionally linked to mitotic history, yet data show strong associations with sleep quality, timing, and light-at-night that persist after controlling for total sleep duration [3, 4, 5, 6].
• Melatonin acts as a potent antioxidant and regulates chromatin remodeling enzymes (e.g., HDACs, HATs) that influence heterochromatin stability [7].
• We propose that melatonin’s primary anti‑aging action at telomeres is to limit the accumulation of epigenetic modifications—such as aberrant DNA methylation and histone variant deposition—that increase the informational entropy of subtelomeric chromatin. Higher entropy promotes a more open chromatin state, exposing telomeric DNA to oxidative damage and impairing shelterin complex binding, thus hastening shortening.

Testable Predictions

1. In vitro: Human fibroblasts exposed to constant light (to suppress melatonin) will show increased subtelomeric methylation variability (measured by bisulfite sequencing) and faster telomere loss compared to melatonin‑supplemented cultures, even when proliferation rates are matched.
2. In vivo: A randomized, double‑blind trial in night‑shift workers will assign participants to melatonin (0.5 mg) or placebo taken 30 minutes before daytime sleep. After 3 months, the melatonin group will exhibit:
   • No change in average sleep duration (actigraphy)
   • Reduced subtelomeric epigenetic entropy (entropy‑score derived from methylation variance at CpGs within 10 kb of telomeres)
   • Attenuated telomere shortening rate (qPCR or Teloseq) relative to placebo.
3. Observational: In cohort data, intra‑individual variability in melatonin metabolite (aMT6s) levels will negatively correlate with subtelomeric methylation entropy after adjusting for age, BMI, and inflammatory markers.

Falsifiability

If melatonin supplementation fails to reduce subtelomeric epigenetic entropy or does not modify telomere shortening kinetics despite confirmed bioavailability, the hypothesis is refuted. Conversely, demonstrating that epigenetic entropy changes precede telomere length alterations and are melatonin‑sensitive would support the mechanistic link.

Implications

Reframing telomere dynamics as a readout of epigenetic entropy integrates circadian biology, oxidative stress, and information theory. It suggests that stabilizing chromatin environment—rather than merely counting divisions—may be a viable strategy to delay cellular aging in populations exposed to chronic circadian disruption.