I was on 20mg of citalopram for about a yr. i have been off of them for a little over a month now & can't sleep. is this typical & how long will it las?

Can happen: It's not typical for a discontinuation (withdrawal) syndrome to last that long, but it's possible. Another possibility is that stopping citalopram has allowed a pre-existing depression or anxiety disorder to return, disturbing your sleep. It can be hard to tell these possibilities apart. Best to discuss it with your prescribing doctor.

It depends: It depends on why you can't sleep. Sometimes insomnia can indicate the beginning of depression or anxiety. If you were taking citalopram for depression and now you have insomnia, it's very important to have your insomnia evaluated and treated. Hope this answer helps.