Facial recognition in late-life insomnia: Preserved positivity bias and associations with negative emotions

Facial emotion recognition (FER) is essential for social functioning. Although aging is typically associated with reduced FER performance, recognition of positive emotions (e.g., happiness) often remains intact-an effect attributed to an age-related positivity bias. However, insomnia, which is highly prevalent in older adults, may disrupt emotional processing and compromise this typically well-preserved component of FER. Yet, few studies have examined the relationship between insomnia and FER specifically in late life.

Fifty-four older adults with insomnia and fifty healthy controls completed a facial emotion recognition task involving happy, sad, fear, and neutral expressions. Groups were matched for age, and gender and education were statistically controlled as covariates in all analyses. Accuracy and response time were analyzed using linear mixed-effects models. Sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI), and correlations between PSQI and FER performance were examined within each group.

No significant group differences were observed in overall FER accuracy. However, emotion-specific patterns emerged: happy expressions were recognized more accurately and rapidly across both groups relative to negative emotions (sadness, fear), consistent with the positivity bias. In addition, exploratory analyses revealed different sleep-emotion patterns across groups: in the control group, a non-significant trend suggested that poorer sleep quality may relate to lower accuracy for happy expressions, whereas in the insomnia group poorer sleep quality was significantly associated with faster and more accurate recognition of negative emotions.

Our findings suggest that the positivity bias in facial emotion recognition remains behaviorally evident in late life but is not fully robust and appears vulnerable to variation in sleep quality. Within-group exploratory analyses further indicated a preliminary association between poorer sleep quality and potential shift in emotional responsiveness to negative emotional cues in older adult with insomnia, without producing a global deficit in recognition accuracy. These patterns highlight the importance of considering sleep quality and emotion-specific profiles, when evaluating emotional functioning in older adults.