Albert Barnes Commentary Jeremiah 51:39

"When they are heated, I will make their feast, and I will make them drunken, that they may rejoice, and sleep a perpetual sleep, and not wake, saith Jehovah." — Jeremiah 51:39 (ASV)

In their heat ... - While, like so many young lions, they are in the full glow of excitement over their prey, God prepares for them a drinking-bout to end in the sleep of death. Compare (Daniel 5:1).