Previous studies have indicated that mindfulness and other forms of meditation training are associated with improvements in sleep quality. However, none of these studies used objective polysomnographic sleep recordings. The aim of this study was to examine whether mindfulness meditation was associated with improvements in objectively measured sleep, according to polysomnography (PSG), and to relate changes in PSG sleep to subjectively reported changes in sleep and depression. This is was a randomized waitlist control trial. The participants were 52 individuals with partially-remitted unipolar recurrent depression, ages 18-65. Approximately 50% of the sample was taking antidepressant medications. Mindfulness-Based Cognitive Therapy (MBCT), an 8-week manualized intervention with a central focus on the practice of mindfulness meditation techniques was used. According to PSG, MBCT was associated with several indices of increased arousal, including less slow-wave sleep, increased arousals, awakenings and stage 1 sleep, relative to controls. An interaction with antidepressant medication use found that arousals, awakenings and stage 1 decreased in the medicated MBCT group. REM sleep changes were minimal. According to sleep diaries, wake after sleep onset (WASO) decreased more in the MBCT group than controls (p<.05). Beck Depression Inventory scores decreased more in the MBCT group than controls (p<.01). Improvements in depression were associated with duration of meditation practice, increased subjective sleep continuity, and increased PSG arousals. Mindfulness meditation is associated with increases in objectively measured arousal during sleep with simultaneous improvements in subjectively reported sleep quality and mood disturbance. This pattern is similar to the profiles of positive responders to common antidepressant medications.