He missed some prayers during Ramadaan because he was asleep. What does he have to do?

Not offering
the prayers at the proper time is a serious matter, concerning which Allaah
has issued a stern warning, as He says (interpretation of the meaning): 

“Then,
there has succeeded them a posterity who have given up As‑Salaah (the
prayers) [i.e. made their Salaah (prayers) to be lost, either by not
offering them or by not offering them perfectly or by not offering them in
their proper fixed times] and have followed lusts. So they will be thrown in
Hell”

[Maryam
19:59]

With regard
to what is meant by ghayy (translated here as “Hell”): 

Ibn ‘Abbaas
(may Allaah be pleased with him) said: it means loss. Qataadah said it means
evil. ‘Abd-Allaah ibn Mas’ood (may Allaah be pleased with him) said it is a
valley in Hell that is very deep and its food is foul. 

See:
Tafseer Ibn Katheer (3/172). 

It was said
to Ibn Mas’ood (may Allaah be pleased with him): Allaah often mentions
prayer in the Qur’aan: “Except those who are devoted to Salaah (prayers)”
[al-Ma’aarij 70:23], “And those who strictly guard their (five
compulsory congregational) Salawaat (prayers) (at their fixed stated hours)”
[al-Mu’minoon 23:9, al-Ma’aarij 70:34], “So woe unto those performers
of Salaah (prayers) (hypocrites), Those who delay their Salaah (prayer from
their stated fixed times)” [al-Ma’oon 107:5]. He said: That warning is
about (not praying) on time. They said: O Abu ‘Abd al-Rahmaan, we thought it
was about not praying at all. He said: Not praying at all is kufr. 

Ta’zeem
Qadr al-Salaah by al-Marwazi (2/5). The editor
said its isnaad is hasan. 

The Prophet
(peace and blessings of Allaah be upon him) mentioned praying and
missing an obligatory prayer as being some of the reasons for which a person
will be punished in the grave. See the answer to question no.
46068 to learn
more about the horror and intensity of this punishment. We ask Allaah to
keep us safe and sound. 

There
follows an exhortation from the great Sahaabi ‘Abd-Allaah ibn Mas’ood (may
Allaah be pleased with him), in which he speaks eloquently of the ruling on
prayer in congregation, the situation of the one who fails to pray in
congregation, the reward of the one who goes to prayer, and the situation of
the one who is eager to go and stand in the row even though he is excused.  

He said: 
“Whoever would like to meet Allaah, may He be exalted, tomorrow as a Muslim,
let him regularly offer these prayers where the call to prayer is given, for
Allaah has prescribed the Sunnahs of guidance to your Prophet (S) and they
(the prayers) are among the Sunnahs of guidance. If you pray in your houses
like this one who stays away from the mosque prays in his house, you will
have forsaken the Sunnah of your Prophet, and if you forsake the Sunnah of
your Prophet you will go astray.” [This is what he said about one who offers
the prayer on time, but he does not pray in congregation in the mosque, and
prays in his house. So what about one who does not pray until the time is
over altogether!] Then he said: There is no man who purifies himself and
purifies himself well, then he goes to one of these mosques, but Allaah will
record one good deed for him for every step he takes, and will raise him in
status one degree thereby, and will erase one bad deed thereby. I remember
when no one would stay away but a hypocrite whose hypocrisy was known, and a
man would come staggering between two others in order to stand in the row. 
Narrated by Muslim (654). 

It is not
right for a Muslim to fast only in the month of Ramadaan. During the year
there are other virtuous days when it is mustahabb to fast, such as the day
of ‘Arafah and ‘Ashoora’. During the week it is mustahabb to fast on Mondays
and Thursdays. During every month it is mustahabb to fast three days of the
month. If you accustomed yourself to fasting all year round, you would not
experience such hardship that makes you sleep all day and miss the prayers. 

You have to
adopt the means that will wake you up for prayer. It is not permissible for
you to deliberately miss prayers on the basis of sleeping when you are able
to wake up at the time for prayer. 

You should
look at the reason why you are so tired when fasting. If it is because of
work, then you should weigh up work and fasting, and if you do not have to
work, and you cannot fast, pray and do other acts of worship because of
work, then you should take a leave of absence from work during the fasting
month. See the answer to question no.
65803 and
43772. If the reason is
staying up late at night, then it haraam for you to stay up late if that is
causing you to miss prayers until the time for them is over. 

You have to
advise your family members, wife and children to wake up for prayer, and
they have to help you to obey Allaah and offer the prayers on time. 

If you have
adopted the means and are still not able to wake up because of intense
tiredness or sickness, and the time for prayer has ended, then you must make
up the prayers that you have missed in the proper order. So you should pray
Zuhr and then ‘Asr and so on, unless you fear that the time for the second
prayer is about to end, in which case you should start with that. If you
wake up before the sun sets and you have not prayed Zuhr and ‘Asr, and so
little time is left for ‘Asr that the sun is about to set, then start with
‘Asr, then pray Zuhr after that, then Maghrib. 

We ask
Allaah, may He be exalted, to help you to obey Him and worship Him well, and
to make you more keen to do good. 

Please also
see the answers to questions no. 38158 and
47123. 

And Allaah
knows best.