Caffeine for the prevention of injuries and errors in shift workers.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 20464765 · doi:10.1002/14651858.CD008508
What was done
A Cochrane systematic review and meta-analysis of randomized controlled trials searched multiple databases (to April 2010) to assess the effects of caffeine on injury, error, or cognitive performance in people with jet lag or shift work disorder. Two authors independently screened studies, extracted data, assessed risk of bias, and pooled effect estimates using a fixed-effect model.
What was found
Thirteen trials were included; none evaluated injury outcomes. Two trials measured error, reporting that caffeine significantly reduced errors compared to placebo. Compared to placebo, caffeine improved memory (SMD -1.08; 95% CI -2.07 to -0.09) and orientation/attention (SMD -0.55; 95% CI -0.83 to -0.27), but did not significantly improve concept formation/reasoning (SMD -0.41; 95% CI -1.04 to 0.23), perception (SMD -0.77; 95% CI -1.73 to 0.20), or verbal functioning/language skills (SMD 0.18; 95% CI -0.50 to 0.87). One trial found caffeine led to significantly fewer errors than a nap, while comparisons to other active interventions (e.g., bright light, modafinil) found no significant differences.
Why it matters
While caffeine reduces errors and enhances specific cognitive domains during circadian misalignment, direct randomized evidence that it reduces actual injuries in shift workers remains lacking.
Limits
No included trials assessed injury outcomes. Findings primarily reflect young participants under simulated laboratory conditions rather than real-world shift workers. Included trials demonstrated a high risk of bias for allocation concealment and selective outcome reporting. Total participant count was not reported in the abstract.
Cited by
- supports Scientific research consistently demonstrates that caffeine acts as a nootropic cognitive enhancer.