This issue comprises two parts. The first part examines pharmacology of drug classes and effects on the slee--wake processes. The second part focuses on therapeutics for various sleep disorders. In the first part, basic neuropharmacology of sleep-wake states is discussed. Other articles review hypnotics, allergy and cardiovascular drugs, anti-convulsant drugs, anti-depressant and anti-psychotic drugs, and stimulants. The second part focuses on pharmacology for specific sleep disorders: primary insomnia, co-morbid insomnia, sleep-related breathing disorders, narcolepsy and disorders of daytime sleepiness, movement disroders, parasomnias, and circadian rhythm disorders.