We're all so different and respond to these meds differently. Even though you've been on it before you may or may not have the same side effects as you did before.
Not being able to sleep could be a side effect from Zoloft. Most side effects usually subside in a few days though.
I was on Zoloft for a lot of years, the only side effect I had was low sex drive, when I got depressed this time I was still on it, and my Psychiatrist took me off it saying it usually only works in the younger age group of people, I am 51. He is very good with medication.
Im On Zoloft now and I'm taking 150mg a day Zoloft made me more sane then the Wellbutrin and my doctor said its the best thing to take while being pregnant idk if sleeping has anything to do with the pill but it is sometimes hard for me to fall asleep and sometimes stay asleep so I take naps during the day I'm a stay at home mom because my husband doesn't want me to work