Sleep deprivation affects people's ability to make moral judgements, a study has shown.
Researchers assessed moral judgements of 26 military personnel at rested baseline and after 53.5 hours of wakefulness. Half of the subjects received caffeine in a chewing gum preparation every two hours throughout each night.
They assessed each individual's response to a series of fictional moral dilemmas categorised into three types.
Moral impersonal dilemmas required volunteers to judge the appropriateness of solutions to dilemmas that would involve deflecting a threat of serious bodily harm onto another individual or a smaller group.
Moral personal dilemmas involved solutions that would inflict serious bodily harm or death to an identified individual in order to reduce the impact of an external threat to another party.
A third type, non-moral decisions, did not lead to serious bodily injury to any character in the scenario.
Researchers found that response time was slower for moral personal dilemmas after 53 hours of wakefulness and also found that participants showed greater difficulty judging whether solutions to emotionally charged moral personal dilemmas were appropriate or inappropriate.
Reaction times for solutions considered 'appropriate' for the tough moral personal dilemmas increased from an average of 6,500 seconds to nearly 9000 seconds.
However, they found that participants with high emotional intelligence were less likely to find decisions difficult when sleep-deprived.