Sayyidah Aisha (may Allah be pleased with her) narrates that the Messenger of Allah (peace and blessings be upon him) said: Bilal gives the adhan during the night (at the time of Tahajjud), so you may eat and drink until Ibn Umm Maktum gives the adhan.
Hadith Referenceالمنتقى ابن الجارود / كتاب الصلاة / 163