If you’re having trouble with sleep, try eliminating caffeine from your diet by lunch time. As a natural central nervous system stimulant, caffeine can rev you up, sometimes for hours. Caffeine has a half-life of three to four hours. That means that half the amount of caffeine you have at lunch is still in your system three to four hours later. One study found that poor sleepers metabolize caffeine at a slower rate.
”There is an association between the daily intake of caffeine, sleep problems and daytime sleepiness.” Coffee and Health Website