We may say we hate Mondays, but research suggests Tuesdays, Wednesdays and Thursdays are equally loathed.
US investigators who looked at a poll of 340,000 people found moods were no worse on Mondays than other working days, bar Friday.
People were happier as they approached the weekend, lending support for the concept of "that Friday feeling".
The report authors told the Journal of Positive Psychology that the concept of miserable Mondays should be ditched.
Prof Arthur Stone of Stony Brook University said: "Despite our global beliefs about lousy Mondays, we conclude that this belief should be abandoned.
"Cultural myths may vastly over-emphasise actual day of the week mood patterns."
Similarly, claims that the Monday of the last full week of January - dubbed "blue Monday" - is the most depressing of the whole year have been debunked by others.
Prof Stone's team analysed data collected by Gallup from telephone interviews.
People reported more enjoyment and happiness and less stress or worry on Fridays, Saturdays and Sundays compared with the rest of the week.
Prof Stone says it is the contrast in mood from Sunday to Monday that has led to Mondays being unfairly singled out.