[The Ruling on Alerting Those Asleep for the Prayer 1]

Answer: One who is awake is not obligated to alert those asleep to perform (for example) the Fajr prayer, and he does not incur sin if he leaves them asleep until the sun rises. However, he has left what is virtuous and recommended, and he has missed out on much good.
The proof that alerting the sleeper for prayer is not obligatory is what is narrated from the Prophet (May Allah bless him and his family and grant them peace): “The pen is lifted from three: from the child until he reaches puberty; from the insane person until he regains his reason; and from the sleeper until he awakes,” or as he said. Thus, prayer is not obligatory upon the sleeper while he is asleep; and if it is not obligatory upon him, then commanding him to it is not obligatory.
As for it being recommended to awaken the sleeper for prayer: it is due to what is narrated of the Prophet’s (May Allah bless him and his family and grant them peace) practice—namely, that on the night when he and his companions slept in the valley, he appointed someone to keep watch and wake them for Fajr; the watchman fell asleep, and the Prophet (May Allah bless him and his family and grant them peace) and his companions were not awakened except by the heat of the sun.
And due to what is narrated that the Prophet (May Allah bless him and his family and grant them peace) used to pass by the door of ʿAlī and Fāṭimah, peace be upon them both, and awaken them for the dawn prayer, saying: “Prayer, O People of the House—‘Indeed, Allah intends only to remove from you the impurity [of sin], O People of the [Prophet’s] Household, and to purify you with [extensive] purification.’” [al-Aḥzāb:33].
And due to what is narrated that the Prophet (May Allah bless him and his family and grant them peace) used to say: “So-and-so gives the call to prayer at night … to awaken your sleepers and to have those standing (in night prayer) return [to rest],” or as he said.
And because of His saying, Exalted is He: “And cooperate in righteousness and piety, but do not cooperate in sin and aggression.” [al-Māʾidah:2]
Source : Min Thimār al-ʿIlm wa al-Ḥikmah vol.1