If you've ever confronted a dishevelled, out-of-sorts coffee drinker first thing in the morning (maybe in the mirror?), you might not find this too surprising: the American Psychiatric Association has officially labelled "caffeine withdrawal" a mental disorder.
The new fifth edition of the Diagnosis and Statistical Manual of Mental Disorders, aka the DSM-5 - it's often called "the psychiatrists' bible" - officially lists caffeine withdrawal as a psychological condition.
"Psychiatrists have noticed that sometimes when you don't have your coffee it's more than just being grumpy in the morning," journalist Jen Wieczner told the Wall Street Journal.
"How much more it's not clear, but things like headaches, trouble sleeping, to the point where it actually interferes with your daily life," she continues.
Check out the discussion about caffeine withdrawal and the DSM-5 in the video below:
Both the new edition and the previous version of the DSM included "caffeine intoxication," where caffeine intake causes distress or impairs mental functions, but withdrawal symptoms were not considered in the fourth edition.
So how much coffee do you need to drink before you're at risk of withdrawal?
"If you drink a lot of coffee, at least two or three cups (236 ml) at a time, there will be a rebound or withdrawal effect," says Dr. Charles O'Brien, chair of the Substance-Related Disorder Work Group for DSM-5.
Not everyone agrees that the condition belongs in the book.
"The symptoms of caffeine withdrawal are transitory, they take care of themselves," clinical psychologist Robin Rosenberg told Yahoo. "It's just a natural response to stopping caffeine, and it clears up on its own in short order."
Caffeine withdrawal is just one condition that's been added to the DSM-5, and the latest revision of the book - the first since 1994 - is generating a lot of controversy, CBC News reports.
Other disorders that are listed in the fifth edition for the first time include marijuana withdrawal, binge eating disorder, and hoarding disorder.
And the definition of attention deficit hyperactivity disorder (ADHD) has changed: before, it was described as a condition unique to children. Now the DSM says ADHD can extend into adulthood.
Some psychiatric experts have expressed concerns about the latest revision.
"[DSM-5] will lower many diagnostic thresholds and increase the number of people in the general population seen as having a mental illness," Professor Peter Kinderman, head of the University of Liverpool's Institute of Psychology, wrote in the BBC's Scrubbing Up column.
"A wide range of unfortunate human behaviours, the subject of many new year's resolutions, will become mental illnesses," he writes. "Excessive eating will become 'binge eating disorder', and the category of 'behavioural addictions' will widen significantly to include such 'disorders' as 'internet addiction' and 'sex addiction'."
As for the psychiatrists who created the latest version of the DSM, they defended their decisions in a statement.
"We have sought to be conservative in our approach to revising DSM-5," writes Dr. David Kupfer, chair of the revisions task force. "Our work has been aimed at more accurately defining mental disorders that have a real impact on people's lives, not expanding the scope of psychiatry."