Brief Answer:
follow the advises.. maintain a healthy lifestyle..

Detailed Answer:
Hello XXXXXXX , Welcome to HCM,
I've gone through your query and understand your concern,

The primary problem seems to be related to your work-shift and inadequate sleep only..

Your too young, and it's always advisable for lifestyle modification prior to any such medications..

You need to sleep properly (~8 hr per day), so night time prior to bed, I'd recommend a cold shower, half an hour of meditation with soothing music, try it, you can google for training video lesson for this before hand..

Make sure to sleep in a completely dark room devoid of any noise..

Try not to take any tea/coffee for at least 3 hrs prior to bed(preferable bed time 11 pm-7 am- practice it, it'll be worthwhile)..

Stay away from any kind of smoking/alcohol (if you do)..

If possible, early morning/evening go out for a light jogging session, you'll be feeling much better and refreshed if maintained in daily basis..

All those stomach related problems are indicating towards IBS(Irritable Bowel Syndrome), that's why you're given those medications in the first place..

Try to indulge in your favorite hobbies/activities, keep your self busy so that all these thoughts don't even get a chance to pop-in your mind..

If despite all these, there's no significant benefit observed, then medications like MELATONIN can be initiated in low dosage (please don't buy over the counter sedatives, as they're not only prone for more harm but also abuse potential)..

But before this, I'd strongly advice you to try all those lifestyle modifications which I've already mentioned, and if still ineffective, then next step will be to consult a Psychologist for a few clinical session of relaxation therapy and active/passive counselling which are much more effective in this scenario than these medications..

Do let me know if there's any further queries.

Take Care
Kind Regards

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