Inquiry:

Was Sisera killed in his sleep? Judges 4:21 says that he was sleeping, but Judges 5:26-27 says he was awake and standing up. Is there a contradiction?
Response:
Judges 4:21 is very concise about Sisera’s death. Jael drove a peg through his skull, effectively nailing him to the ground.
Judges 5:26-27 gives additional information. It says:
She put her hand to the nail, and her right hand to the workmen’s hammer; and with the hammer she smote Sisera, she smote off his head, when she had pierced and stricken through his temples. At her feet he bowed, he fell, he lay down: at her feet he bowed, he fell, where he bowed, there he fell down dead.
First, I will have you note that Judges 5:26-27 does not say Sisera was awake and standing up; that’s the questioner’s statement, not the Bible writer’s. Judges 4:21 tells us he was asleep when Jael drove the nail into his head, and Judges 5:26-27 indicates that he was abruptly wakened. He did not die instantly.
The words “bowed,” “fell,” and “lay” are no doubt the trouble for the questioner. These are used to describe the pitiful state of his convulsing body before death, not a man who was alert and standing up, but failed to duck when Jael came at him with a tent peg. Look at each word:
Bowed – Heb. עֵרֶךְ
…to sink …cast down …fall, feeble, kneeling, …smite, subdue. (Strong’s)
Fell – Heb. נָפַל
…to fall, …cast down, cease, die, divide, fail, fall, …laying, overthrow, over-whelm, perish. (Strong’s)
Lay – Heb. שָׁכַב
…to lie down, cast down, lay, …ravish, take rest. (Strong’s)
As a child, I had a dog who was hit by a car. It struck his head. He did not die instantly. Despite his crushed skull, he got up, stumbled a few steps, and fell down. This continued until he was mercifully killed. I imagine Sisera’s experience was similar. Despite the head wound, he attempted to get up, fell over, tried again, and eventually died.
There is no contradiction.