Hypothesis

Combining morning bright light exposure (≥10,000 lux, 30 min upon waking), evening blue‑light blocking glasses (446‑483 nm) from sunset to bedtime, and an early time‑restricted eating window (8 am–4 pm) will act synergistically to raise nocturnal hepatic NAD+ levels, enhance SIRT1 deacetylase activity, and thereby amplify the amplitude of core circadian clock genes (BMAL1, CLOCK, PER2) in humans.

Mechanistic Rationale

1. Melatonin suppression by evening blue light reduces NAMPT transcription, limiting the NAD+ salvage pathway and lowering SIRT1 activity【1†https://pubmed.ncbi.nlm.nih.gov/23509952/】.
2. Morning bright light advances the cortisol awakening response and stimulates AMPK, which increases NAMPT expression and NAD+ synthesis【7†https://medicalxpress.com/news/2025-09-americans-healthier-permanent-standard.html】.
3. Early time‑restricted eating aligns nutrient‑sensing pathways (mTORC1 inhibition, AMPK activation) with the endogenous NAD+ oscillation peak that occurs during the early active phase【5†https://www.utsouthwestern.edu/newsroom/articles/year-2022/active-phase-calorie-restriction.html】.
4. Elevated NAD+ fuels SIRT1‑mediated deacetylation of BMAL1 and PER2, strengthening transcriptional feedback loops and increasing the robustness of circadian rhythms【2†https://www.chronobiologyinmedicine.org/m/journal/view.php?number=167】.
5. Stronger circadian rhythms improve sleep architecture, particularly frontal slow‑wave activity, reducing metabolic inflammation and delaying age‑related decline【3†https://www.frontiersin.org/journals/aging/articles/10.3389/fragi.2025.1646794/full】.

Testable Predictions

• In a randomized crossover trial, participants receiving the triple intervention will show a ≥15 % increase in evening plasma NAD+ compared with baseline and with single‑intervention arms (blue‑blockers only or TRE only).
• SIRT1 activity in peripheral blood mononuclear cells, measured by a deacetylation assay of a p53 peptide, will be significantly higher after the triple intervention (p < 0.01).
• Actigraphy and polysomnography will reveal a ≥10 % increase in frontal slow‑wave power (2‑4 Hz) during the first NREM cycle and a reduction in sleep onset latency.
• If NAD+ levels fail to rise or SIRT1 activity does not increase despite adherence to the protocol, the hypothesis is falsified.

Novel Insight

The hypothesis posits that melatonin’s role extends beyond sleep promotion to a direct regulator of the NAD+ salvage pathway; thus, protecting melatonin synthesis via blue‑blockade is a metabolic intervention that, when paired with circadian‑aligned light and feeding cues, creates a positive feedback loop that sustains youthful circadian physiology.