They may feel better simply because they are correcting the symptoms of caffeine withdrawal, researchers say.

Caffeine withdrawal may also contribute; you probably are not drinking the gallons you need during the week to power through your office hours.

For habitual users, your morning coffee merely reverses the symptoms of caffeine withdrawal, returning you to normal function.

You get afflicted by cabin fever and caffeine withdrawal in equal measures.

For some people, however, caffeine withdrawal only makes them doubly stubborn.