Actually I'llI have a night shift tomorrow ( technically from tonight tountil tomorrow's morning). I have a night shift tomorrow ( technically from tonight until tomorrow morning).

"actually" at the start of the sentence is only really used when we're correcting someone, best to leave it out here "tomorrow morning" is fine, no need for a possessive there

Actually, I'll have a night shift tomorrow ( technically from tonight to tomorrow's morning). Actually, I have a night shift tomorrow (technically from tonight to tomorrow morning).

A reminder that "actually" does not mean "currently / right now" as is a common misconception for English learners. "Actually" is typically said before something that may come as surprising/unexpected. So if you include the word here, it carries a small meaning that you may think we as readers will find it a bit unusual.

Actually, I'll have a am working the night shift tomorrow (it is technically from tonight to tomorrow's morning). Actually, I am working the night shift tomorrow (it is technically from tonight to tomorrow morning).

Most of the time it's better practice to add a comma (",") after you begin a sentence with "actually"

I'm glad that overall work time in night shifts is lessare shorter than normal shifts' one, but Ithey cause me to lose my sense of time and give met a headache. I'm glad that night shifts are shorter than normal shifts, but they cause me to lose my sense of time and give me a headache.

Rephrasing for more natural flow, and keeping the subject as the night shifts.

I'm glad that there is less overall work time during night shifts is less thancompared to normal/day shifts' one, but I lose my sense of time and get a headaches. I'm glad that there is less overall work during night shifts compared to normal/day shifts, but I lose my sense of time and get headaches.

There are two possible meanings from the first part of your sentence. You might be saying that you have less work to do (more idle time), or you might be saying that the shift is shorter (the time/duration total is less, we are not speaking about how much work is done). I understood it as the former since it is typical for work to be slow (not a lot to do) at night. Something that happens habitually/recurringly, write it as: I get headaches

I'm glad that overall work time in night shifts is lessI work for fewer hours during the night shift than during thane normal shifts' one, bu. However, during the night shift I lose my sense of time and get a headache. I'm glad that I work for fewer hours during the night shift than during the normal shift. However, during the night shift I lose my sense of time and get a headache.

I guess it can't be helped since it's work. I guess it can't be helped since it's work.

This is fine, but I probably would word it a bit differently. E.g., I guess it can't be helped, work is work.