Cues of fatigue: effects of sleep deprivation on facial appearance

Abstract

Study objective: To investigate the facial cues by which one recognizes that someone is sleep deprived versus not sleep deprived.

Design: Experimental laboratory study.

Setting: Karolinska Institutet, Stockholm, Sweden.

Participants: Forty observers (20 women, mean age 25 ± 5 y) rated 20 facial photographs with respect to fatigue, 10 facial cues, and sadness. The stimulus material consisted of 10 individuals (five women) photographed at 14:30 after normal sleep and after 31 h of sleep deprivation following a night with 5 h of sleep.

Measurements: Ratings of fatigue, fatigue-related cues, and sadness in facial photographs.

Results: The faces of sleep deprived individuals were perceived as having more hanging eyelids, redder eyes, more swollen eyes, darker circles under the eyes, paler skin, more wrinkles/fine lines, and more droopy corners of the mouth (effects ranging from b = +3 ± 1 to b = +15 ± 1 mm on 100-mm visual analog scales, P < 0.01). The ratings of fatigue were related to glazed eyes and to all the cues affected by sleep deprivation (P < 0.01). Ratings of rash/eczema or tense lips were not significantly affected by sleep deprivation, nor associated with judgements of fatigue. In addition, sleep-deprived individuals looked sadder than after normal sleep, and sadness was related to looking fatigued (P < 0.01).

Conclusions: The results show that sleep deprivation affects features relating to the eyes, mouth, and skin, and that these features function as cues of sleep loss to other people. Because these facial regions are important in the communication between humans, facial cues of sleep deprivation and fatigue may carry social consequences for the sleep deprived individual in everyday life.

Keywords: Photo ratings; cues of fatigue; facial cues; sleep deprivation.

Figure 1

Relationships between rated fatigue and facial cues. The figure illustrates how high fatigue ratings were related to high ratings on hanging eyelids, red eyes, swollen eyes, and glazed eyes. High ratings of fatigue were also related to dark circles under the eyes, pale skin, and wrinkles/fine lines around the eyes, but not rash/eczema. In addition, high ratings of fatigue relate to droopy corners of the mouth and sadness, but not tense lips. The plots consist of 778-800 ratings each (40 observers rated 20 photos) on 100 mm visual analogue scales. The relationships are based on the models presented in Table 1, with the variation between observers removed (by means of Empirical Bayes estimates). Thus, all observers have been adjusted (in level) to represent an average observer.