This research aims to determine if melatonin supplementation, through improvements in sleep quality, increases the ability to repair oxidative DNA damage and reduce lipid peroxidation levels among nightshift workers.

Administering a 3 mg melatonin supplement to nightshift workers prior to day sleep may significantly improve their oxidative DNA damage repair capacity and reduce the occurrence of lipid peroxidation [measured as increased excretion of urinary 8-hydroxydeoxyguanosine (8-OH-dG) and decreased excretion of urinary 8-isoprostane, respectively] through improvements in sleep quality (measured via actigraphy) and melatonin's direct antioxidative properties.

Eligibility criteria included: 1) living and working in the Greater Vancouver area; 2) being between the ages of 18 and 50; 3) having a body mass index (BMI) between 18.5 and 30 kg/m2; 4) working at least two consecutive night shifts per week (≥7 hours per night ending no earlier than 06:00) for at least six months; 5) sleeping, on average, six hours during day sleep periods; 6) not currently using marijuana or illicit drugs; 7) no personal history of sleep disorders, hormone disorders, seizure disorders, or chronic medical conditions (e.g., cancer, diabetes, kidney disease, liver disease, asthma, cardiovascular disease, and infectious disease); 8) not currently pregnant or currently breast feeding; 9) no trans-meridian travel within fours weeks of data collection; and 10) not currently using melatonin supplements.