The night prayer (tahajjud): time and method

The night prayer (tahajjud) occupies the time from the end of isha until dawn appears. The scholars agree: the whole night is a time for the voluntary prayer, and the witr, the last prayer of the night, remains valid until dawn bursts; its first time opens as soon as isha ends.

The method: two by two

The night prayer is performed two by two; if one of you fears the arrival of dawn, let him pray one single rak'a: it will make odd all that he has prayed.Muslim 736

So pray in pairs of rak'as, at your own pace, and conclude with the witr.

Seated or lying down, the door stays open

The body tires and sleep calls. The voluntary night prayer remains valid seated or lying down, with a smaller reward, according to the Prophet's answer (peace and blessings of Allah be upon him) to 'Imran ibn Husayn: standing is best; seated, half the reward of standing; lying down, half of the seated. Among the Hanafis, praying lying down is a permitted choice, and one is free between standing up or beginning seated.

Practical note

Fix a real portion of night, even a short one: two rak'as before falling back asleep, then the witr. Wake a second time if strength is lacking the first time. What matters in the night is the presence of the heart, not the length.