Can invega (paliperidone) be used to treat severe insmnia?

Yes but: It can cause a lot of side effects. It would be appropriate if you have schizophrenia or bipolar disorder schizoaffective disorder to be on it. However for other types of mental illness related insomnia it's probably not the best idea. The weight gain can be significant, there are elevated prolactin levels, a high risk of diabetes, hypercholesterolemia, hypertriglyceridemia, and a risk of tardiva dyskinesia.

No: It is not indicated for treatment of insomnia. Invega (paliperidone) is only fda approved for schizophrenia and schizoaffective disorder. There are multiple other insomnia medications that your provide shoulder explore before using the aforementioned psychotropic.