Welcome to Just Answer !
Well, yes you are right in saying that if one is devoid of sleep , then ,it definitely takes a toll on one's daily routine and there is some sort of functional impairment.
Now, as far as your bewilderment regarding which drug to take at night , out of seroquel ( quetiapine) or remeron ( mirtazapine), well, both these drugs are good for inducing sleep in insomnia , but i would prefer remeron ( mirtazapine) , which is an anti depressant , with an additive sedative effect , so i would suggest you shall go for remeron (mirtazapine) , and take 15 mg of remeron at night before sleep in addition to your 30 mg dose , the reason i cite for preferring remeron is due to the fact that , although both the mentioned drugs act as good sedatives, but remeron is a safer drug , with least side effects attatched to it.
So, you shall call your doctor , and just let him know of this , i am sure he will comply with your request and allow you to take remeron at night , however if at all, the need arises for an alternative , then there is a very tried and tested drug , with worldwide usage as a drug for insomnia and is FDA approved , and that is AMBIEN CR ( ZOLPIDEM), to be taken only at night before sleep , plus is a very safe drug as well. So, you may also ask your doctor about the use of this drug along with remeron from your doctor , but since your doctor is not here , and you can get ambien cr through prescription , so i would suggest you take an additional remeron 15 mg at night , but do make it a point to inform your doctor.
So, i suggest you do the needful , as mentioed above and i am quite sure your insomnia will get sorted.
I wish you best of health.
I hope my answer serves your query according to your satisfaction.