OBJECTIVES: Previous work suggests that sleep restriction (SR) reduces cognitive control and may increase negative implicit biases. Here we investigated whether SR might influence decision making on a social-evaluative task where individuals had to make judgments of threat based on facial photographs. Furthermore, we investigated the effect of changes in negative implicit biases as a result of sleep restriction on this decision-making task.
DESIGN: Fourteen healthy adults underwent two 3-week counterbalanced in-laboratory stays (chronic SR and control sleep [CS] conditions). Participants completed the Arab Muslim Names implicit association test (a measure of implicit bias/attitudes toward Arab Muslims) and the Karolinska Airport Task (a measure of explicit decision making). The Karolinska Airport Task requires participants to judge the potential dangerousness of individuals based on facial photographs.
RESULTS: After SR, participants were more likely to deem individuals with less positive and more negative facial features as dangerous than after CS. In addition, after SR, those participants showing higher negative implicit bias toward Arab Muslims tended to consider as more dangerous individuals with more quintessentially untrustworthy facial features (r = 0.76, P = .007), whereas this relationship was nonsignificant after CS (r = 0.33, P = .28).
CONCLUSIONS: These findings show not only that SR may increase implicit biases against a particular minority group but that SR also modifies how individuals make explicit decisions about another's trustworthiness based on facial features. These findings may have important implications for many occupations where workers who are routinely restricted of sleep are also responsible for making judgments about other people's trustworthiness (eg, police, security, military personnel).