Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
awhile (adv.), a while (determiner plus noun)
Lie down awhile, and get some sleep illustrates the adverb, which is spelled as one word. Take a while to get oriented and Lie down for a while, and get some sleep illustrate the determiner a plus the noun it modifies. For many uses, only writing it will distinguish which syntactic structure you use.
