Dreaming at your desk about your recent vacation? Having trouble concentrating? Feeling depressed and wishing you were anywhere but at work? You are not alone.

Doctors don't officially have a name for this. There's nothing specific in the official manual of mental disorders. But the Twitterverse calls your sadness #backtoworkblues or #holidayblues.

Feel familiar? This crankiness about the first day back to work is perfectly normal according to Dr. Angelos Halaris, a professor of psychiatry and behavioral neurosciences at Loyola University in Illinois, CNN reports.

"The stark contrast of the joy and freedom of family and friend time with the drudgery of answering a zillion work emails, can be hard on your emotional well-being," he said.

It's not just adults, either. A 2017 study found adolescent depression, anxiety and feelings about everyday hassles appeared to be tied to the end and beginning of school-vacation cycles. It might come as no surprise that teens felt less anxious and depressed during the vacation.

Halaris said it's not unusual for people to react badly to their return to work for the first couple of weeks.

"There is a real sense of loss that comes with this transition period that makes us all a little sad," Halaris said.