Ambulatory home monitoring has been employed for a number of applications. Portable sleep/wake recorders are useful for assessment of the hypersomnias, circadian sleep/wake disorders, parasomnias, and periodic movements in sleep. Wrist actigraphy can usefully approximate sleep versus wake state during 24 h and has been used for monitoring insomnia, circadian sleep/wake disturbances, and periodic limb movement disorder. Home monitoring of cardiopulmonary parameters can be employed for detection and follow-up of sleep-disordered breathing (sleep apnea, upper airway resistance syndrome). The techniques available for portable monitoring, although valuable, do not replace traditional in-laboratory polysomnography for full assessment of a sleep disorder.