Elevated plasma homocysteine in older shift-workers: a potential risk factor for cardiovascular morbidity.

There is evidence supporting an association between shift work and cardiovascular morbidity, but the underlying mechanisms are unknown. The present paper investigated the levels of cardiovascular biochemical risk factors in shift-workers both with (n=26) and without (n=103) sleep complaints, and in day-workers (n=173) working in the same plant. Blood samples were taken in the morning after an overnight fast and analyzed for homocysteine, C-reactive protein, and lipid profile. Biochemical data were compared among groups after stratifying workers by age (i.e., <40 and > or = 40 yrs). Shift-workers who complained about sleep disturbances and who were > or = 40 years of age had significantly higher levels of homocysteine than did their younger counterparts - shift-workers who did not complain of sleep disturbances and day-workers. There were no other between-group differences in any of the biochemical variables. The results of this investigation demonstrate an association between sleep disturbances in older shift-workers and mild hyperhomocysteinemia. The elevated homocysteine levels may play a role in the increased rates of cardiovascular morbidity in shift-workers, and they may have practical implications regarding the nutrition of shift-workers.