Almost all people with Lewy body dementia (LBD) will have had sleep disturbances before they develop dementia symptoms, often those considered predementia symptoms such as rapid eye movement (REM) sleep behavior disorder (RBD). Of course, these sleep issues continue after dementia shows up. Two of the most prominent sleep-related problems appear to be at odds with each other: RBD disturbs sleep and excessive day-time sleeping (EDS) causes too much sleep. However, both are easily within the realm of elements common to LBD: vivid-but-not-real experiences and a general slowing down of all body functions. The literature occasionally mentions insomnia as a symptom, but caregivers seldom do. Usually, disturbed nighttime sleep is caused by the active dreams of RBD, the interrupted breathing of sleep apnea, or the irritations of restless leg syndrome (RLS), another sleep disorder common with Lewy body dementia.