Caffeine withdrawal

With repetitive use of Caffeine, physical dependence or caffiene addiction may occur. Also, some effects of caffeine, particularly the autonomic effects, decrease over time, a phenomenon known as a tolerance. Tolerance develops quickly to some (but not all) effects of caffeine, especially among heavy coffee and energy drink consumers. Some coffee drinkers develop tolerance to its sleep-disrupting effects, but others apparently do not.

Withdrawal
Withdrawal symptoms – including headaches, irritability, impaired concentration, drowsiness, insomnia, and pain in the stomach, upper body, and joints – may appear within 12 to 24 hours after discontinuation of caffeine intake, peak at roughly 48 hours, and usually last from 2 to 9 days. Withdrawal headaches are experienced by 52% of people who stopped consuming caffeine for two days after an average of 235 mg caffeine per day prior to that. In prolonged caffeine drinkers, symptoms such as increased depression and anxiety, nausea, vomiting, physical pains and intense desire for caffeine containing beverages are also reported. Peer knowledge, support and interaction may aid withdrawal.

Caffeine withdrawal is categorized as a mental disorder in the DSM-5 (the 5th edition of the Diagnostic and Statistical Manual published by the American Psychiatric Association). Previous versions of the manual included "caffeine intoxication" but not caffeine withdrawal.