ABSTRACT
The reasons for sleep are identified and discussed, along with the adverse physical and mental effects of sleep loss. The physiology of the waking state, REM and NREM sleep are explained, linked to electroencephalograms of the waking state and sleep stages. The sleep–wake cycle is explained. The suprachiasmatic nucleus is explained in relation to the 24-hour sleep–wake cycle and the effects of external light levels. Dreams and nightmares are discussed. Sleep disorders are identified and explored, in particular insomnia and narcolepsy, and the genes linked to sleep disorders are explained. The pharmacodynamics and pharmacokinetics of drugs used to promote sleep are explained.
