Assallamu Alaikum
In order to perform Thahajjud Namaz is it necessary to awake from sleep? Or at an appointed time could Thahjjud Namaz be performed?
الجواب حامدا و مصلیا
It is not necessary to sleep and awake to perform Thahajjud Namaz. Without doing so it could also be performed at an appointed time.