Let's learn something new today.

1. Sleep (noun/verb):

   • As a noun: "I need to get enough sleep."
   • As a verb: "I sleep for eight hours every night."

2. Asleep (adverb):

   • It is primarily used as an adverb to describe the state of being asleep: "She fell asleep quickly." Here, "asleep" describes how she fell, indicating the state of sleepiness.

So, while "sleep" can function as both a noun and a verb, "asleep" is specifically used as an adverb to describe the state of being in sleep.