down for the count

having failed in doing or achieving something and unable to continue

The idiom "down for the count" is believed to have originated in the sport of boxing, where a boxer who is knocked down by their opponent must remain on the mat for a count of ten before they can continue the fight. This phrase is often used more broadly to describe a person who has been defeated or overcome, whether in a physical or metaphorical sense.

He has been fighting the illness for weeks, and now he's down for the count.
The company is struggling to stay afloat, and it looks like they might be down for the count.
The team is down for the count after losing their star player to an injury.

(of a boxer) knocked down and unable to stand up and continue the fight within the referee's ten-second count

sleeping so soundly that one cannot be easily awakened

The idiom "down for the count" originally comes from the sport of boxing, where it was used to describe a fighter who had been knocked down by their opponent and was temporarily unable to continue the match. In boxing, the referee would count to ten, and if the downed fighter didn't rise before the count of ten, they were declared the loser. Over time, the phrase has been extended to describe someone who is temporarily incapacitated, exhausted, or overwhelmed, particularly in the context of sleep or fatigue.

After pulling an all-nighter to meet the deadline, I was down for the count and needed a long nap.
The flu hit me hard, and I was down for the count, spending most of the weekend in bed.
Following the intense workout, my muscles were sore, and I felt down for the count, struggling to get up from the couch.
The long-haul flight left me feeling completely drained, and I was down for the count when I arrived at my destination.
She had been working nonstop for days, and by the time the weekend came, she was down for the count, barely able to get out of bed.