Table 4 Human studies on NSW and melatonin
From: Night shift work and breast cancer: from etiopathology to precision risk analysis
NSW Effect | Parameter(s) | Outcome | Year | Ref. |
|---|---|---|---|---|
Circadian adaptation after ~1 week of sustained NSW | Urinary 6-SMT | → Phase delay (successful entrainment) | 1998 | |
Seasonal dependence of MEL rhythm adjustment | Urinary 6-SMT | → Phase advance (spring); ↔ no adaptation (winter) | 1998 | |
Disrupted MEL rhythm and poor sleep | Urinary 6-OHMS ratio (sleep:work) | ↓ MEL; ↓ sleep quality; ↑ fatigue | 2005 | |
Non-significant reduction in MEL | Urinary aMT6s | slight MEL ↓ | 2006 | |
Persistent suppression during and after NSW | Urinary 6-SMT (nurses) | ↓ MEL on work and off days | 2006 | |
Reduced post-shift MEL, timing unchanged | Urinary MEL | ↓ Levels after night shifts | 2009 | |
Light-dependent desynchrony | Urinary 6-SMT | ↓ Total MEL; → circadian misalignment | 2012 | |
Chronic suppression and potential cancer risk | Urinary 6-SMT (male NSW) | ↓ MEL across sleep periods | 2013 | |
No measurable change (few NSW exposures) | Urinary aMT6s | ↔ MEL | 2014 | |
Delayed and reduced MEL peak | Urinary MEL | ↓ MEL; → delayed acrophase | 2014 | |
Progressive decline with simulated NSW | Urinary MEL | ↓ Nighttime and 24-h secretion | 2014 | |
Suppressed amplitude with consecutive NSW | Salivary MEL | ↓ Amplitude ≈ 4.9% day⁻¹; ↔ phase | 2016 | |
Reduced mesor and phase advance | Urinary aMT6s | ↓ MEL; → earlier peak | 2016 | |
Global summary of MEL disruption | Review | ↓ Overall production; → gradual misalignment | 2017 | |
Transient, light-mediated suppression | Salivary MEL | ↓ 15–16% on workdays; ↔ off-days | 2017 | |
Gene-shift interaction in BC risk | MTNR1A, CRY2, RORA polymorphisms | NSW ↑ BC risk in high-risk genotypes | 2019 | |
Lower MEL linked to metabolic risk | Plasma MEL (nurses) | ↓ MEL; possible metabolic impact | 2019 | |
Social jetlag correlated with suppression | Urinary aMT6s | ↓ MEL with ↑ SJL | 2021 | |
Epigenetic alterations in circadian genes | Urinary 6-SMT + DNA methylation (RORA, MTNR1A, PER3) | Altered methylation; ↓ MEL | 2022 | |
Light-intensity–dependent suppression | Salivary MEL | ↓ with high nocturnal light; → delayed rhythm | 2023 | |
MEL supplementation improved sleep and cognition | Oral MEL 5 mg post-shift | ↑ Sleep quality; ↑ cognitive performance | 2024 | |
MEL improved oxidative DNA repair | Urinary 8-OH-dG + aMT6s | ↑ 8-OH-dG excretion; ↑ aMT6s | 2025 | |
No effect on metabolism | Oral MEL 0.3 mg q.o.d. | ↔ Body composition; ↔ intake | 2025 | |
No alteration in salivary MEL rhythm | Salivary MEL (day vs night) | ↔ Circadian rhythm | 2025 |
