Enervated, 4 letters
Far from peppy, 4 letters
Feeling sluggish, 4 letters
Half-awake, 4 letters
In the dumps, 4 letters
Lacking energy, 4 letters
Lacking pep, 4 letters
Lethargic, 4 letters
Lethargic after lunch, 4 letters
Mentally sluggish, 4 letters
Sluggish, 4 letters
Sluggish from overeating, 4 letters
Stuporous, 4 letters