A bad night of sleep can make itself known in a myriad of unexpected ways. Perhaps one of the most interesting is the discovery that not sleeping enough seems to make you worse at identifying faces. This effect is likely more or less unnoticeable for the average person, but for someone working in a field where facial recognition is crucial, like security or policing, the effect could have serious repercussions. It also stands to reason that a person whose facial recognition capability is impaired would make a less reliable eyewitness in criminal cases.
In a study published by Royal Society Open Science, participants were assessed for sleep disorders before being shown pairs of faces: some were photos of the same face, while others were similar but different faces. Participants with insomnia were not only worse at correctly identifying which pairs showed photos of different people, but were more confident in their incorrect answers.
The experiment was then repeated with a group of well-rested people versus a group who had had less sleep than normal for a few days, but were not diagnosed with a sleep disorder. As expected, the poor sleep group was worse than the well-rested group at identifying faces. However, unlike the insomniac group, this group was not more confident in their wrong answers. They were not, however, any less confident in their answers than well-rested people.
The researchers noted that even though this experiment shows a correlation between poor sleep and an impaired ability to recognize faces, there may not be a direct causal link—for instance, the anxiety and mood impairments that themselves result from bad sleep may be responsible for the discrepancy. They suggested that future research on this subject should experimentally restrict sleep.
Deficits in working memory, attention, and visual perception that result from poor sleep are thought to contribute to this impairment, but the relative importance of each of these mechanisms was not measured in this study (researchers pointed to this as another potential avenue for future research). Regardless of the causal details, this study is yet another reason everyone should make sleep a priority—especially if their careers make them responsible for other people’s safety and well-being!