It is difficult for him to pray qiyaam because of his work situation and because he is a heavy sleeper
Question

                My work situation means that I work all night and I sleep in the day. It is difficult for me to get up and offer the four other prayers, because I get so tired at work. I cannot get up whilst I am sleeping and do the prayers and then go back to sleep. And there is another reason, which is that I am a heavy sleeper, and when I sleep no one can wake me up, even if I intend to get up and pray during the day.
Praise be to Allah.Firstly: 
Some of the 
    Sahaabah (may Allaah be pleased with them) used to do difficult work such as 
    farming, herding livestock, gathering firewood and so on, but they did not 
    neglect their prayers, rather they used to observe the prayers regularly, 
    not just on time but also in congregation. They were regular in praying and 
    seeking knowledge, and they were not granted any concession allowing them 
    not to pray because of work. 
Hence it is 
    obligatory for those who work and others to offer the prayers on time. 
    Allaah praises the believers who do not let their work distract them from 
    obeying Allaah, as He says (interpretation of the meaning): 
“Men whom 
    neither trade nor sale (business) diverts from the remembrance of Allaah 
    (with heart and tongue) nor from performing As‑Salaat (Iqaamat‑as‑Salaat) 
    nor from giving the Zakaah. They fear a Day when hearts and eyes will be 
    overturned (out of the horror of the torment of the Day of Resurrection).
38. That 
    Allaah may reward them according to the best of their deeds, and add even 
    more for them out of His Grace. And Allaah provides without measure to whom 
    He wills”
[al-Noor 
    24:37-38]
Secondly: 
The one who 
    sleeps is excused at the time when he is sleeping, but when he wakes up it 
    becomes obligatory for him to perform the prayer after he has woken up. 
It was 
    narrated that Anas ibn Maalik (may Allaah be pleased with him) said: The 
    Prophet of Allaah  (peace and blessings of Allaah be upon him) said: 
    “Whoever forgets a prayer or sleeps and misses it, the expiation for that is 
    to pray it when he remembers it.” Narrated by al-Bukhaari (572) and Muslim 
    (684). 
This hadeeth 
    indicates that the one who sleeps is not accountable during the time of his 
    sleep, and there is consensus on this point. 
The apparent 
    meaning of the hadeeth is that there is no negligence in sleep if a person 
    sleeps before the time for prayer begins or after that but before the time 
    becomes too short. And it was said that if a person deliberately goes to 
    sleep before the time becomes too short and he takes that as a means of not 
    praying because he thinks it most likely that he will not wake up until the 
    time for the prayer is over, then he is sinning. But the apparent meaning is 
    that there is no sin on him because of sleeping, because he did that at a 
    time when it was permissible to do it, so he is included in this hadeeth. 
    But if he did it deliberately in order to miss the prayer, then there is no 
    doubt that he is sinning thereby. End quote. 
Nayl 
    al-Awtaar 2/33, 34. 
Thirdly: 
What a 
    person should do before going to sleep is to be keen to wake up at the time 
    of prayer, and to take the means that will help him to perform the prayer on 
    time. If he does that but does not wake up, then he is excused because he 
    did what he had to, and “Allaah burdens not a person beyond his scope” 
    [al-Baqarah 2:286]. That happened to the Prophet  (peace and 
    blessings of Allaah be upon him) on some of his journeys. 
It was 
    narrated that Abu Qataadah (may Allaah be pleased with him) said: “We 
    travelled with the Messenger of Allaah  (peace and blessings of Allaah 
    be upon him) by night and some of the people said: “Why don’t you let us 
    stop at the end of the night so that we may rest, O Messenger of Allaah?” He 
    said: “I am afraid that you will sleep and miss the prayer.” Bilaal said: I 
    will wake you up.” So they lay down and Bilaal leaned his back against his 
    mount, but his eyes grew heavy and he slept. Then the Prophet  (peace 
    and blessings of Allaah be upon him) woke up when the sun had risen. And he 
    said: “O Bilaal, what about what you said?” He said: “I have never slept 
    like that before.” He said: “Allaah took your souls when He willed and 
    returned them to you when He willed. O Bilaal, get up and call the people to 
    prayer.” And he did wudoo’ when the sun had risen high and turned white, 
    then he stood and prayed. Narrated by al-Bukhaari (570) and Muslim (681).  
The Prophet 
     (peace and blessings of Allaah be upon him) took the means of waking up 
    by appointing Bilaal to alert them when it was time to pray, but sleep 
    overtook him, and he and the people slept until the sun had risen. They were 
    not negligent, hence the Prophet  (peace and blessings of Allaah be upon 
    him) said, “There is no neglect among the people.” 
As for one 
    who stays up all night because of work etc and does not take the means and 
    prays after the time for the prayer is over, he is regarded as deliberately 
    not praying, and he is not excused because of his sleep. 
Shaykh 
    Muhammad ibn Saalih al-‘Uthaymeen (may Allaah have mercy on him) was asked 
    about someone who stays up all night and is not able to pray Fajr until 
    after the time for it is over – will it be accepted from him? And what is 
    the ruling on the rest of the prayers which he offers on time? 
He replied: 
With regard 
    to Fajr prayer which he delays until the time for it is over when he is able 
    to offer it on time, because he could sleep early, this prayer of his will 
    not be accepted from him, because the Prophet  (peace and blessings of 
    Allaah be upon him) said: “Whoever does an action that is not in accordance 
    with this matter of ours will have it rejected.” Narrated by Muslim. The one 
    who deliberately delays a prayer until the time for it is over, with no 
    excuse, will have it rejected, because he has done something that is not in 
    accordance with the command of Allaah and His Messenger, so it will be 
    rejected. 
But he may 
    say: I was asleep, and the Prophet  (peace and blessings of Allaah be 
    upon him) said: “Whoever sleeps and misses a prayer or forgets it, let him 
    pray it when he remembers it, for there is no expiation for it but that.” 
We say: If 
    he could have slept early so that he would wake up early, or he could have 
    set an alarm clock to wake him up, or he could have asked someone to wake 
    him up, then his delaying the prayer and not getting up for it is regarded 
    as deliberately delaying the prayer, so it will not be accepted from him. 
    End quote. 
Majmoo’ 
    Fataawa al-Shaykh Ibn ‘Uthaymeen, 12/question no. 
    14 
Fourthly: 
A man may be 
    a heavy sleeper, and one of two scenarios must apply: 
1 – He 
    sleeps deeply because he has stayed up at night to work, seek knowledge or 
    pray qiyaam. In this case it is not permissible for him to miss performing 
    prayers on time because of that, and he should look for another job that 
    will not cause him to miss the prayers. Similarly it is not permissible for 
    him to let naafil deeds – even seeking knowledge, which is basically 
    obligatory – distract him and cause him to miss the prayers. In this case 
    his not praying is regarded as deliberate, because he could change his job 
    and he could avoid staying up at night. 
Shaykh 
    Muhammad ibn Saalih al-‘Uthaymeen (may Allaah have mercy on him) said: 
What our 
    brothers who go on trips should do is thank Allaah for this blessing, as He 
    has made them prosperous and given them a life of comfort and ease, in an 
    atmosphere of safety and freedom from fear, and they should do what Allaah 
    has enjoined on them of praying on time, whether that is Fajr prayer or any 
    other. It is not permissible for them to delay Fajr prayer on the basis that 
    they are sleeping, because in most cases there is no excuse for this sleep, 
    because they can use alarm clocks to wake them up to pray on time, and they 
    can sleep early so that they can wake up refreshed. End quote. 
Majmoo’ 
    Fataawa al-Shaykh Ibn ‘Uthaymeen (12/question no. 
    14) 
2 – A person 
    may be a naturally heavy sleeper, and it has nothing to do with work or 
    staying up at night. This is known in the case of some individuals. If that 
    is the case, then he is excused if he takes the means but does not wake up. 
It was 
    narrated that Abu Sa’eed al-Khudri (may Allaah be pleased with him) said: A 
    woman came to the Prophet  (peace and blessings of Allaah be upon him) 
    when we were with him and said: “O Messenger of Allaah, my husband Safwaan 
    ibn al-Mu’attal does not pray Fajr until the sun has risen.” Safwaan was 
    with him, so he asked him about what she had said, and he said: “O Messenger 
    of Allaah, we are a family who are known not to wake up until the sun has 
    risen.” He said: “When you wake up, then pray.” Narrated by Abu Dawood, 
    2459; classed as saheeh by Shaykh al-Albaani in Irwa’ al-Ghaleel, 
    7/65 
Conclusion: 
    in your case it seems that your sleeping heavily has to do with staying up 
    at night, and you are staying up at night because of work. On this basis, it 
    is not permissible for you to stay in that job, because it is causing you to 
    forsake the most important pillar of Islam after the Shahaadatayn. So look 
    for another job, and Allaah will compensate you with something better than 
    it. You will see a change for the better in your religious commitment, your 
    body and your mental attitude. As for your religious commitment, performing 
    the prayers on time is one of the most important duties, and not doing it is 
    one of the worst of haraam actions. As for your body, the doctors have 
    described many harmful effects suffered by those who work at night; sleeping 
    during the day does not give the body the same rest as sleeping at night 
    does. And all of that has a negative effect on one's mental attitude. 
And Allaah 
    knows best.