I was reading my kids a bedtime story and accidentally fell asleep prior to Davening Maariv and woke up at five in the morning. May I still Daven Maariv?
Since five in the morning in your locality is past Alos Hashachar but before sunrise, therefore you are to only Daven Maariv until the blessing of Goal Yisrael, and not recite the blessing of Hashkiveinu, nor are you to Daven Shemoneh Esrei. Tomorrow morning by Shacharis you should Daven Shemoneh Esrei again as a Tashlumin for Maariv. You are not to read the morning Shema until after sunrise.
Explanation: Just as the reading of the morning Shema has a start and end time, so too, the nighttime Shema of Maariv has a start time and end time to fulfill the Biblical obligation. Now, ideally, the end time for the reading of the night Shema of Maariv is [at least Rabbinically] by daybreak, which is Alos Hashachar, and hence one must read the Shema prior to this time and if he reads it after this time he does not fulfill his obligation. However, the Poskim explain that if one did not read the night Shema prior to Alos Hashachar due to reasons beyond his control, then the Sages permitted him to still read it even past Alos Hashachar and fulfill his Biblical obligation. In such a case, it may be read up until sunrise. In such a case one is to read the before and after blessings of the Shema together with the Shema, with exception to the blessing of Hashkiveinu which is not to be recited once it is after Alos Hashachar being that is no longer a time for people to go to sleep. If however he did not read the Shema prior to Alos due to negligence and reasons that were within his control [and according to some opinions even if this was due to mere forgetfulness], the sages removed his ability of fulfilling his Biblical obligation of reading the Shema, although if he chooses he may read it without its blessings like a person who reads verses from the Torah.
Reasons beyond one’s control: Now, what is defined as “reasons beyond one’s control”? Is one who went to sleep prior to reading the Shema and woke up after the time of Alos Hashachar considered to have not read it due to reasons beyond his control? This question especially applies if he could’ve read the Shema before he went to sleep and did not do so. So, the Michaber gives an example of a person who was drunk or sick and the like, as an example of one did not read due to reasons beyond his control. Many Achronim explain [although some argue] that even if the person got himself drunk after nightfall when he could have already read the Shema, nonetheless, since he relied on the fact that he has much time remaining to read the Shema therefore if he only became sober after Alos Hashachar it is considered beyond his control, and only if he became drunk close to the morning with his lack of saying the shall not be considered not due to reasons beyond his control. Now, the example of being drunk can be viewed similar to one who falls asleep prior to reading the Shema, even if he put himself to sleep after nightfall, and hence he too should be permitted to recite the Shema with its blessings if he wakes up after Alos Hashachar, and so indeed rule some Achronim.
Shemoneh Esrei: It is debated amongst the Achronim if whether a person who did not Daven Maariv prior to Alos due to reasons beyond his control is likewise to Daven Shemoneh Esrei prior to sunrise after he recites Shema with its blessings. Some rule that it is only regarding Shema that it can be fulfilled until sunrise while the rabbinical prayer of Shemoneh Esrei of Maariv expires immediately by Alos and hence can no longer be prayed and therefore the above individual will pray an abridged form of maariv without saying Shemoneh Esrei. Others however rule that one may even Daven Maariv Shemoneh Esrei before sunrise. Practically, Safek Brachos Lihakel, and hence he should not Daven Maariv Shemoneh Esrei at all and rather Daven Shemoneh Esrei of Shacharis twice as Tashlumin. Alternatively, he should Daven Maariv Shemoneh Esrei as a Tnaiy Nedava and then again Daven a second Shemoneh Esrei after Shacharis was as a Tnaiy Nedava.
Sources: See Michaber and Rama 235:4; Rambam Tefila 3:6; M”B 235:34; Shaar Hatziyon 235:41; Kaf Hachaim 235:29-30; Ketzos Hashulchan 27:3; Piskeiy Teshuvos 235:11-12; See regarding the definition of reasons beyond his control: Michaber ibid; Even if he drank after nightfall it is considered out of his control: Elya Raba 235:12; Mamar Mordechai 235:9; M”B 235:31 and chapter 99; See also Admur 99:1 and 108:11; Other opinions: Taz 235:4 and Nehar Shalom 235:3 [is like Meizid]; P”M 235 M”Z 4 and Kaf Hachaim 235:25 [Say Shema without Brachos due to Safek]; See regarding the status of one who fell asleep: Shulchan Hatahor 235:5 [is like drunk]; Chesed Lealafim 235:4 [is like Meizid]; Piskeiy Teshuvos ibid footnotes 70-71 See regarding that when he read it up until sunrise: Biur Halacha 235:4 “Acher”; See regarding that biblically the time for reading the night Shema is until sunrise and is just that the sages nullified its reading past Alos Hashachar: M”B 235:30; Shaar Hatziyon 235:4; Kaf Hachaim 235:25 See regarding the debate if the prayer of Shemoneh Esrei should also be said: No: M”B 235:34; Rambam Tefila 3:6; Kaf Hachaim 235:25; See Shaar Hatziyon 235:42 Yes: Aruch Hashulchan 235:19; Hisorerus Teshuvah 1:113 [Daven Nedava]; See Maharil Diskin Kuntrus Achron 2:5-29; Piskeiy Teshuovs ibid See regarding not reading the morning Shema until after sunrise: Ketzos Hashulchan 27:3; See Kaf Hachaim 235:31