Long ago the French identified a combination of boredom, feelings of meaningless futility and homesickness as a deadly combination for young enlisted soldiers both conscript and volunteer. The condition was termed Caffard and was a recognized cause of death and entered on death certificates under ‘cause of mortality’. Drugs kill but the endless mindless boredom of junior enlisted life sets one up to try any potential palliative.
Do you mean ‘’L’ennui’’?