using present prog. tense to express future action

[Applejoy]

Question : Are both sentences grammatically correct?If yes,is there a difference in meaning?I read that we can use simple present and present progressive to express future action in time clauses.

a. I'm going to listen to music while I sleep tonight.
b. I'm going to listen to music while I'm sleeping tonight.

Thanks!

[Tdol]

They're both correct. There's not much difference between them, but often the use of the progressive form can emphasise duration, though with sleep, which normally has a fairly standard duration, it doesn't make much difference. If you had something like while I wait/am waiting, the difference might be clearer. -)