Those who, due to work or the necessity to sleep, find it difficult to do their Hour at the corresponding time of the day or night can move it to a time that makes it easier for them to do it well. For example, if someone has one of the night Hours, say from 3 to 4 A.M., he can do it before going to bed. However, from time to time he may want to make the sacrifice of getting up at that hour of the night to offer Jesus this effort too. However, we do not recommend you to take extra time from work to read the Hour of the Passion.
Regardless of the situation you in, you should always have the intention and true desire to read your assigned Hour of the Passion even when you can not do it for some days due to lack of time or unforeseeable circumstances.
In the Prayer of Preparation before each Hour, we say:
"...And for the hours I cannot meditate, I offer You the will I have to meditate them, and I propose to meditate them with my intention during all the hours I must dedicate myself to my duties or sleep…." (The Hours of the Passion, Prayer of Preparation before each Hour)
This also refers to those days when for unforeseeable circumstances, sickness or occupations, you cannot read the assigned Hour of the Passion.