Dreaming is defined as mental activity which occurs during sleep. This review will focus on sleep disorders which have been studied in relation to dreaming: insomnia, sleep apnea syndrome, narcolepsy, and the restless legs syndrome. Dream recall is heightened in patients with insomnia and their dreams reflect current stressors. Whereas breathing-related dreams in sleep apnea patients are rare, the deregulation of the REM sleep system in narcolepsy also manifests in dreams which are more bizarre and more negatively toned. Overall, the findings support the arousal-retrieval model of dream recall but also clearly indicate that other factors like cognitive impairment or micro-arousal might affect the dreaming process. The content analytic findings support the continuity hypothesis of dreaming which states that waking-life issues are reflected in dreams. The number of studies in this field is still very small, however, and further research is needed to confirm and expand the reviewed findings.