Q: I get of work at 1 am. i want 2 prep 4 ramadan. Can I perform tahajud salah and go2bed or must I get up from sleep2perform it? Can1do it after isha salah or would it nt count as tahajud? (text)
A: Ideal conditions would be for a person to remove him/herself from their sleep so as to maximize their reward. Thus, getting up from ones sleep and praying the tahajud salah would reap more reward then performing it after the isha salah, even though doing it after the isha salah would allow for its acceptance and represents its permissibility.
Should getting up from your sleep be impossible, performing it after isha with the intention of it being tahajud salah or performing it prior to going to sleep would also allow for it to be called the tahajud salah.
Allah Certainly Knows Best.