Yesterday i started citalopram, if it keeps me from sleeping initially, can i take zolpidem to sleep? how long do initial citalopram side fx last?

Yes you can: It is not unusual to experience a stimulating effect from antidepressants. Sometimes this wears off and sometimes it doesn't. Insomnia associated with the antidepressant is common. A trial of sleeping medicine is reasonable on a short term basis. Also, insomnia can be related to the depression itself. When the depression is treated, the sleeping med can be discontinued. Best wishes!