The Oxford Thesaurus An A-Z Dictionary of Synonyms - lethargyn.

1) sluggishness, sloth, dullness, heaviness, laziness, indolence, phlegm, idleness, languidness, languor, listlessness, dolce far niente, inactivity, inertia, torpor, stupor; indifference, apathy: After taking the medicine, a feeling of lethargy overtook me. 2) weariness, tiredness, fatigue, weakness, exhaustion, drowsiness, sleepiness, somnolence: The strident persistence of my alarm clock dragged me out of my lethargy.