Has anyone else heard of mirtazapine being prescribed only as needed for insomina?

I've been using mirtazapine for just over 2 weeks for insomnia and even after only 2 nights of 15mg dosage I felt withdrawals on night 5, where I lay awake with anxiety (something previously foreign to me), after the previous 2 nights sleeping without the drug. It stays in the body for a few days before being eliminated so it may be easier to develop a dependence than you realise. Best to try sleeping drugs that have no physical dependence issues before going on to something like mirtazapine, in my view. Others may have a different experience.

Some doctors now prescribe it off label as a sleep aid. The idea is to knock you out so it should only be taken as needed in this case. It is usually prescribed daily for depression. Due to the dependency psych drugs cause, you should only take it as needed unless you are treating depression. Taking it daily will drastically increase your chances of having withdrawal when you no longer need the drug.

Yes. Mirtazapine is often prescribed off label just for insomnia. It is a powerful sleep aid. The lower doses are more effective for insomnia (it's counter intuitive) I'd start off with the 7.5 mg first or even lower ( get a pill splitter) at 3.5 mg. Give it a couple of weeks. If the lower dose doesn't help increase it but I would not go above the 15 mg. At 30 and 45mg it has much more antidepressant effect and if you aren't depressed you don't need or want that.
One of the disadvantages is that some people have a difficult time stopping. Rebound insomnia is common with cessation. But it it's better to sleep than not and if this helps you get the rest you need it's worth it in my opinion.

I am not a physician so if you have any questions please talk to your doctor. Good luck and I hope you get well.