If I wake up early in the morning, like any time from 2am to 6am, before Alot Hashachar, and I'm pretty sure I'll start my day and not go back to sleep, at least not before a possible afternoon nap, what can I do in terms of hand washing, birchat hashachar, birchat haTorah, learning Torah, drinking something, doing exercise, and eating a snack or a meal? I'm never sure what to do, and I end up neither eating, drinking, nor learning Torah until after the time to say brachot, or even until after netz. I'd prefer to use these quiet, early hours to learn Torah or work on my religious studies and religious research than to read secular material or watch videos or clean the house, if I can, so I'd really like to know what is permissible. Thank you so much for this site and for your help.
Birkot HaShachar can, according to the Magen Avraham (47:13), can be said as early as midnight, but I'm not sure if that's the general custom, because I've noticed that people usually wait until alot hashachar.
In general, the Shulchan Aruch (89:3) says that you can't perform anything for yourself, but doing things for the purposes of a mitzvah is ok. Based on this, the Mishnah Berurah allows buying food for Shabbos if the markets are only open in the morning (there, seif katan 36) and R' Shlomo Zalman Auerbach (quoted in Tefilah Kehilchasa 6:36) allows doing anything for one's wife and family, as these are acts of chesed.
Eating: The Mishna Berura (S"A 89:5, Mishna Berura 27) says that you shouldn't eat a meal beginning from half an hour before alot hashachar. Before that time, though, it is not recommended by kabbalah but otherwise assumed to be allowed (Aruch Hashulchan 89:26).
Drinking: according to the Aruch Hashulchan (89:23) drinking coffee or tea with milk and sugar, if that's the normal way of drinking it, is allowed before davening (even after Alot Hashachar).
Learning: as above, Birkas HaTorah can be said before dawn (47:13), and if one fell asleep during the day, even before midnight (Mishna Berura there, seif katan 28)
Exercising: In "Halakhically Speaking" volume 1, the author quotes Rabbi Belsky as saying that if one's intent by exercising is to be stronger for 'avodas Hashem', it can be done before davening.