Is it wrong or a sin study today?
For laziness I didn’t study to my two test of tomorrow.
I went to Mass today.
So I intend to study the whole night, Is it a sin?
Studying is for students a condition of their state of life. This means it is a duty and it can become a prayer when we unite it to the work of Christ, one that can benefit souls and give glory to the Lord.
It is not good, however, to disregard your health. One must have an orderly way of doing things, and take responsibility for what goes wrong. Studying all night is quite often necessary when there is no other way out - but if it becomes a habit, it greatly harms us physically but especially mentally. That ought to stimulate us to be more productive, that we may sleep a sufficient amount of time every night.
Also, this is a result of a vice, and vice leads to sin. Trust me, as someone who is always a student, I understand that we often term laziness what sometimes truly isn’t, but I also know the truth of the saying “laziness is the father of all vices”. Often, fixes, patches and finding our way out or around even through amazing and praiseworthy efforts simply reinforces our laziness - we become more and more “last minute people” and what is worse, we become prideful because we trust in ourselves - we think we can do it, we can manage to survive at the last minute. But we don’t get rid of a vice unless we hate its cause and replace it with a virtue. Thus, we must develop a distaste for wasting time and going off schedule, and become more diligent and committed to our schedule (a good way is to work hard on keeping fixed prayer times - they will help the rest of the day fall into the right places).
Going to Holy Mass is not the way out of honoring the Lord’s Day

The precept of Holy Church is that we must attend Holy Mass on the Lord’s Day and other Holy Days of Obligation - not that this fulfills the
Third Commandment. "The Sunday Eucharist is the foundation and confirmation of all Christian practice. Participation in the communal celebration of the Sunday Eucharist is a testimony of belonging and of being faithful to Christ and to his Church. "
The Third Commandment reminds us that the Lord’s Day, “the fist day of the week”, is a sacred, solemn day. It is not about not doing anything, but about respecting its holiness and remember that just like we need enough sleep at night, we need that one day for our own physical, mental, and spiritual health. Jesus said: “
The sabbath was made for man, not man for the sabbath. My Father is always at his work to this very day, and I too am working. The Son of Man is lord even of the sabbath.”. Properly understood, this signifies that we can and must still fulfill the obligations of our state of life and do God’s will, but unlike an ordinary day, this day is the Lord’s - so we must try to spend time with Him and find refreshment that will be needed for the rest of the week. Or, as the Catechism nicely states:
the faithful are to refrain from engaging in work or activities that hinder the worship owed to God, the joy proper to the Lord’s Day, the performance of the works of mercy, and the appropriate relaxation of mind and body.
The faithful should see to it that legitimate excuses do not lead to habits prejudicial to religion, family life, and health.
Every Christian should avoid making unnecessary demands on others that would hinder them from observing the Lord’s Day.
But the Catechism also reminds us of our obligations and the duty they impose on us by quoting St. Augustine, who brings both things together:
The charity of truth seeks holy leisure- the necessity of charity accepts just work.
Wish you well on your exam!