Extending previous research on the psychological costs of sleep deprivation, the present study examined the impact of insufficient sleep on the capacity to be mindful as well as on the satisfaction of individuals’ basic psychological needs, two psychological sources of mental health. The interrelationship between these two psychological resources and fatigue following sleep deprivation was also examined. Participants were 49 adults (77% female; Mage = 32.81 years, SD = 13.09 years) who were randomly assigned to either an experimental (N = 23) or a control (N = 26) group. The study had a 4-day within-person design. In the experimental group, a baseline assessment day was followed by 3 days of partial sleep deprivation (i.e., 5-h sleep per night), whereas participants in the control group slept as usual across the 4-day period. Participants rated their fatigue and psychological functioning each evening and wore an actigraph watch which monitored their sleep. Participants reported increased fatigue after 1 day of sleep deprivation, whereas it took 3 days of sleep deprivation before their mindfulness and need satisfaction deteriorated. Mediational analyses indicated that decreased need satisfaction after 3 days of sleep deprivation was completely accounted for (i.e., explained) by increased fatigue and subsequent decreases in mindfulness. These findings build on previous research by showing that mindfulness and need-based experiences not only precede but also follow from sleep at night.