*Address for Correspondence: Dr. Garima Shukla, Professor, Department of Neurology Room No. 2, 6th Floor, Neurosciences Center All India Institute of Medical Sciences New Delhi, India. Tel:
The intricate interplay between circadian and ultradian processes and rhythms that determine sleepiness and wakefulness in normal human adults has been widely studied and has been excellently presented in the form of mathematical models interweaving homeostatic, circadian, and ultradian processes. The evolution of knowledge about these and the clinical applications of this view about sleep regulationhave been discussed in this review.
