Waking up to grammar: why "laying awake" is a mistake

What kind of error is it?

It is a grammatical error involving the misuse of verb forms.

Why do people make this mistake?

People often confuse "lay" and "lie" because their past tenses ('laid" and "lay" respectively) are similar, and "lay" is also a transitive verb involving an action on an object, while "lie" is intransitive and does not require an object.

What is correct?

"Lying awake" is correct because "lie" is the intransitive verb that means to recline or be in a horizontal position. The present participle of "lie" is "lying."