Objective To raise awareness within the Defence Medical Services regarding the potential effect of post-alcohol impairment / alcohol hangover.

Method Literature relating to post-alcohol impairment / alcohol hangover, and the evidence for impairment is reviewed, with discussion relating to UK Armed Forces.

Conclusion The evidence for performance impairment during alcohol hangover is not conclusive. Until further evidence is available policy should acknowledge the potential for impaired functioning, particularly the morning after a heavy drinking session, and even when blood alcohol has returned to zero. Recommendations for clinical practice and areas for further research are presented.