Doldrums aren’t drums that you can play like the tom-toms. Rather people use this noun to describe a period of time that is boring, depressing, or characterized by inactivity.
The noun doldrums is derived from the word dull. If you’ve been vegging out in front of the TV for hours, bored out of your mind, you might say you’re "in the doldrums." This word is often used in phrases describing a slump in the economy or as in “the summer doldrums” to describe the hot, lazy days of summer.