Torpor
/ˈtɔːrpər/ noun hardA state of mental or physical sluggishness and lack of energy or activity.
The heavy lunch left the whole office in a torpor for the rest of the afternoon.
Memory Trick
Torpor is the root behind 'torpedo,' the electric ray once thought to numb anyone who touched it -- torpor is that same numbing, sluggish feeling spreading through your whole body.