8:3 Some authorities are of the opinion that if a person wakes up at midnight that he may not eat. The Kitzur Shulchan Aruch advises following the stringent opinion in this matter unless a person physically needs to strengthen himself in order to function. The Mishnah Brurah (89:28) cites the Pri Megadim that this rule only applies if one slept (as opposed to staying up) and even then, drinking might be okay. He concludes that, according to the letter of the law, even one who slept might eat and drink if he awoke before daybreak, though it’s still good to follow the stringent opinion if one is able.
8:4 Water, tea and coffee (without milk or sugar) may be drunk before praying, even after dawn, because drinking these simple beverages (all of which are basically water) is not considered paying too much attention to one’s own needs. (Mishnah Brurah 89:22 acknowledges that some people simply don’t function before their morning cup.) This is the case even before praying on Shabbos and Yom Tov; the absence of having recited kiddush is not an impediment because one does not have an obligation in kiddush until after he has prayed. Kiddush must be recited before eating a proper meal, which one may not do before praying in any event.