Background
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. Despite this, the relationship between insomnia and FER in late life remains underexplored.


Methods
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.


Results
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. Exploratory analyses further suggested group-specific sleep-emotion associations: in the control group, a non-significant trend indicated that poorer sleep quality may be associated with lower accuracy for happy expressions, whereas in the insomnia group poorer sleep quality was significantly related to faster and more accurate recognition of negative emotions.


Conclusion
Our findings suggest that the positivity bias in facial emotion recognition remains behaviorally evident in late life but is potentially vulnerable to variation in sleep quality. Within-group exploratory findings further point to a possible shift toward heightened responsiveness to negative emotional cues in older adults 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 adulthood.