Why is the region near the equator sometimes called the dolldrums?

A meteorological term, doldrums are areas where the space between the trade winds is so large that little or no wind is present, this happens most often north of the equator and in both the Atlantic and the Pacific. It was something to be avoided by sailing ships for obvious reasons, because they could be becalmed. The term doldrums also means stagnation, a sluggish state in which something fails to develop or improve. Thirdly it means Gloominess or state of low energy