Background: Sleep disturbance is increasingly common worldwide and is linked to a wide range of negative health outcomes. Emerging evidence suggests it may also influence prosocial behaviors, voluntary actions intended to benefit others, an important contributor to individuals' well-being and social cohesion. However, most studies have examined only one type of prosocial behavior, and few have tested bidirectional, longitudinal links between sleep and diverse prosocial behaviors. Using a two-wave design, this study examined the bidirectional temporal relationships between sleep disturbance and three types of prosocial behaviors.
Methods: An online survey was completed by 601 adults from Hong Kong (420 females; Mage = 35.46, SDage = 12.19) at two time points, six months apart. Sleep disturbance was measured with the Pittsburgh Sleep Quality Index, and prosocial behaviors were assessed using the Hong Kong Altruism Index, capturing formal volunteering, informal helping, and extraordinary prosocial behaviors (i.e., blood and organ donation). A two-wave cross-lagged panel model was employed to examine the longitudinal associations.
Results: Lower sleep disturbance at Wave 1 predicted higher extraordinary prosocial behaviors (β = -0.047, 95% CI [-0.091, -0.002], p = .040) but lower formal volunteering (β = 0.127, 95% CI [0.033, 0.220], p = .008) at Wave 2, and was unrelated to informal helping. In the reverse direction, formal volunteering and informal helping at Wave 1 did not predict later sleep disturbance. However, Wave 1 extraordinary prosocial behaviors showed a trend-level association with reduced Wave 2 sleep disturbance (β = -0.048, 95% CI [-0.098, 0.002], p = .060).
Conclusions: Lower sleep disturbance may foster subsequent extraordinary prosocial behaviors but reduce formal volunteering. A potential reciprocal link between sleep disturbance and extraordinary prosocial behaviors warrants further investigation. Future research should investigate the mechanisms underlying these bidirectional associations and determine whether interventions targeted one domain can benefit the other.