This chapter makes a distinction between studies of sleepiness and studies of napping. In considering difficulties with excessive daytime sleepiness among older adults, one key factor is poor quality nighttime sleep. Many studies have found that depression is associated with excessive daytime sleepiness (EDS), with some of those studies focusing specifically on older adults. One key treatment consideration in the management of daytime sleepiness among older adults is to address primary sleep disorders that disrupt nighttime sleep. One such example is a randomized controlled trial of the effect of treatment of sleep apnea on daytime functioning in patients with Alzhiemer's disease (AD). Studies show that patients with dementia, particularly with AD, commonly suffer from daytime sleepiness. Studies also highlight that increased exposure to bright light, particularly when combined with efforts to reduce time in bed during the day, may be an effective method for decreasing daytime sleepiness.

Sleep paralysis is classified as a parasomnia associated with rapid-eye-movement periods (REMPs). The paralysis is consistent with atonia observed during normal REMPs produced by hyperpolarization of the spinal motoneurons originating in cholinoceptive neurons in dorsolateral regions of the pontine reticular formation. Estimates of RISP prevalence vary dramatically, yielding estimates between 6% and 40%. Sleep paralysis is often considered as a sleep-onset problem under the assumption that episodes occur at the beginning of the sleep period during Sleep Onset REM Period (SOREMP). Multiphase sleep-wake schedule (MPS) regimes likely produce high level of cognitive arousal precipitating episodes by increasing potential for waking during immediate post-interruption REMPs. Vestibular-motor (V-M) hallucinations likely arise via interactions between subcortical and cortical vestibular centers. RISP associated with a variety of affective disorders including depression, panic disorder, PTSD, and social anxiety. RISP has typically been thought to reflect anomalies of the functioning of monoaminergic and/or cholinergic neural systems.