There is a wide-spread minhag to stay up all night on the evening of Shavuot and learn until shacharit in the morning. I know that when people do that, there are some necessary changes to the morning davening. What are some of the halachic issues that come up with morning davening after staying up all night and how are those issues properly addressed?
Eating before davening
The first issue that can come up is the prohibition to eat before davening shacharit. In many places where groups of people gather to have an all-night learning seder, food is provided. Once the time of alot ha-shachar arrives, one should stop eating or else he has violated the prohibition of eating before davening.
Next, there are a few morning brachos that you cannot say if you have not slept. They are as follows with proper actions listed in order of preference:
- Have someone who has slept lying down for 30+ minutes recite the blessing and have you in mind to fulfill your obligation.
- If there is no one around who slept 30+ minutes, have in mind to be yotzei with the bracha of Mechayeh Meitim in Shmoneh Esrei.
- Simply go without this bracha.
- Have someone who has slept lying down for 30+ minutes recite the blessings and have you in mind to fulfill your obligation. (Then say yevarechecha and eilu devarim to yourself.)
- Have in mind for the bracha of Ahava Rabba to count for birchot haTorah. Then make sure to learn something at some point after shemoneh esrei.
- If you did not do the first two options, have someone getting up when you get home (perhaps your wife) say it for you or ask a person getting an aliya to have you in mind with the first bracha and then read quietly along for a few pesukim.
- Simply go without
Hama'avir Sheina Me-eynai
- Have someone who has slept lying down for 30+ minutes recite the blessing and have you in mind to fulfill your obligation (note the yehi ratzon paragraph that follows the first line is part of the bracha. Do not reply amein until after gomel chasadim tovim le-amo Yisrael).
- Have someone getting up at home (perhaps your wife) say it for you when you get home.
- Simply go without
The bracha on al mitzvat tzitzit on a tallit katan.
- If you wear a tallit gadol, after Mi-she-yakir make a bracha on your tallit gadol having in mind the tzitzit that you are wearing.
- If you don't wear a tallit gadol have someone who does be motzi you with his bracha.
- Make a bracha on a different pair of tzitzit and put them on (you can do this when you get home assuming you don't have a separate tallit katan at shul)
- Just keep wearing your tzitzit but don't make a bracha.
- It is generally the case in most shuls that one person who slept the previous night will be appointed to be motzi everybody else with the brachot that they cannot say.
- When you are being yotzei by someone else's bracha, you should respond amein to the bracha, but not barukh hu u-varukh shemo (see here).
- This answer is largely based on a document entitled "Shavuos Morning: A Guide to the Weary and Perplexed" compiled by R' Kalman Zinnes handed out at shacharit davening this past Shavuot at a shul in Chicago.