The heat sapped his energy and sent thoughts of sleep tumbling through his head.

There is a desire to be there, in the fight, but the heat is sapping even that.

And in summer the heat saps a fighting force.

Even without him exerting any real effort, the heat and humidity were sapping his energy.

But the intense heat of the sun radiating up from the salt floor was sapping Mathew's strength.

The heat sapped strength and energy, so that feet stumbled and heads bowed.

Maybe the heat was sapping him, but he just didn't feel like getting into an argument.

David marched to sector 53 and knelt, the heat sapping his energy.

They could do nothing more as they were, and the heat was sapping them.

But soon the heat and the heavy, stagnant air sapped even adrenaline-pumped will.