Caffeine metabolism and coffee-attributed sleep disturbances

In six healthy subjects with a history of caffeine-induced wakefulness caffeine kinetics were compared to with those in six subjects not affected by caffeine. The data indicated that the former have a longer plasma t½ (mean 7.4 and 4.2 hr) and slower plasma clearance (mean 1.2 and 1.7 ml · min−1 · kg−1) of caffeine. Plasma caffeine concentration at midnight, 8 hr after afternoon coffee, is higher in those with caffeine-attributed insomnia. Those reporting "coffee wakefulness" also tend to drink less coffee. We conclude that the rate of caffeine metabolism is a determinant of individual variation in the effect of drinking coffee on sleep. Clinical Pharmacology and Therapeutics (1983) 33, 770–775; doi:10.1038/clpt.1983.105