insomnia caused by anxiety

[nobutan]

A while back, I had insomnia, I couldn't sleep until sunrise. That time a tragedy happened in my family (my sister's 2nd bipolar manic episode) and the whole family was stressful and sad. That time, at night I became anxious and afraid of the dark and I had to leave the light on in order to sleep. But soon, I can't even sleep even with the lights on, I was feeling very insecure and afraid of what I cannot see after I turn off the lights. Then soon, I don't dare to close my eyes even with the lights on.
But I'm good now, but still once in a while I wake up at night and I know I had to turn on the light to sleep again, then I wake up again at sunrise to turn it off. Also want to mention that I tend to be afraid of the dark.
I realize that I tend to become anxious during school breaks, when I have so much time.

Also want to mention that I'm the kind of person that don't feel right when I am wasting time and not achieving anything.

Also want to mention that I have IBS, but not always with diarrhea.

I'm a Capricorn too.

My question is what is wrong with me? Why I tend to feel anxious? I sometimes suddenly feel anxious at night too, I don't know why.