"his tender"
Metaphor
Act 3,
Scene 2
Lines 82-87
Demetrius
Demetrius compares a sleep deficit to a money deficit. Sorrow causes you to lose sleep, which causes your sorrow to become heavier, resulting in a still larger sleep deficit. Likewise, interest payments on a debt reduce your cash flow, which results in more borrowing, resulting in an even larger debt, ending in bankruptcy. Demetrius is going to pay down his sleep deficit by resting here a while.