[sleep] like a dog

to sleep in a way that one cannot be easily woken up

After a long day of hiking, he was so exhausted that he collapsed on the couch and slept like a dog.
The baby finally settled down and began to sleep like a dog, giving her parents a much-needed break.
After spending the whole weekend relaxing, she felt refreshed and ready to take on the week, having slept like a dog.
He loved lazy Sundays when he could sleep like a dog, taking long naps without any interruptions.
With the soft rain falling outside, she curled up under a blanket and slept like a dog, completely unaware of the world around her.