An essential component of optimal functioning consists of the ability to recuperate from daily stressful assaults, to repair cellular damage, and to rebuild the mental, emotional, and physical capacity to respond to and cope with the next days stressors (i.e., stress resilience; Fig. 1, column 2). A significant opportunity for restoration occurs during sleep. Inadequate sleep has adverse consequences,including suppression of cellular immune responses(Irwin, 2002). Aging is associated with decrements in sleep quality, including increases in time spent awake at night and decreases in sleep depth (Floyd, 2002). As many as 50% of adults over age 65 complain of sleep problems (Foley et al., 1995), making sleep-related immune changes a serious concern among the elderly. Stress, loneliness, and depression all may make sleep less restful and restorative, therefore diminishing the effectiveness of nightly restorative processes. We are currently conducting longitudinal research to examine the extent to which the diminution of restorative processes (e.g., sleep) due to stress contributes to the aging of the immune system across the lifespan.