An expanded set of techniques, together called chronotherapeutics, combines light therapy, wake therapy (sleep deprivation) and sleep phase advance therapy. It is particularly useful for inducing rapid, sustained remission in patients with depression. Many of these patients have the late circadian rhythm tendency seen in delayed sleep phase disorders. Indeed, many patients with delayed sleep phase syndrome become depressed. A 2009 treatment manual has been published, Chronotherapeutics for Affective Disorders.