Insomnia is diagnostically characterized by difficulty in initiating and maintaining sleep, and is usually accompanied by subjective complaints of nonrefreshing sleep and behavioral impairments during the day. There may be evidence of increased heart rate and sympathetic tone (Bonnet and Arand, 1995), increased cerebral glucose metabolism during both wake and sleep states (Nofzinger et al., 2004), and activation of the hypothalamic-pituitary-adrenal (HPA) axis (Vgontzas et al., 2001) in patients with insomnia indicating central nervous system hyperarousal. Hypnotics are commonly used to treat this condition but it is important that improved sleep is not achieved at the expense of next-day functioning due to residual drug effects.