What Are The Side Effects Of Sleeping Pills ?

Hi I have been on duromine 30mg for 12 weeks now and have been totally fine on it until the last 3-4 days when I have had trouble sleeping at night. I know this is a side effect but I have only just getting it after taking it for 12 weeks. Would ii be ok for me to take a sleeping pill on some nights that I can not get to sleep? Thanks