This study examined the relationship between changes in social interactions and sleep status, specifically sleep duration and restoration, among older adults in Japan to inform interventions for healthy aging. A 6-year longitudinal study (2017–2023) was conducted under the Community Empowerment and Care Project in suburban Japan. A total of 473 older adults with normal sleep in 2017 were followed. Sleep duration (< 6 h defined as deprivation) and sleep restoration (subjective restfulness) were assessed according to national guidelines. Social interaction was measured using the 18-item Index of Social Interaction (ISI). Changes in the ISI were analyzed continuously and categorically. Lo-gistic regression models were used to examine the association between ISI changes and sleep outcomes. After six years, 16.3% of the participants experienced sleep deprivation, and 26.2% reported non-restorative sleep. Declining ISI scores were significantly asso-ciated with a higher risk of sleep deprivation and non-restorative sleep. Persistently low or declining ISI scores increased the odds of poor sleep. A one-point ISI increase re-duced the risk of sleep deprivation and non-restorative sleep, even after adjusting for confounders. Negative or persistently low social interaction is linked to worse sleep outcomes; maintaining or improving social interaction may protect sleep quality.