Clozapine Withdrawal is Brutal
Here is one of many articles documenting just how difficult it is to get off of Clozapine (Just search the Inter-Webs!):
Clozapine discontinuation withdrawal symptoms in schizophrenia

I suffered for months with this. I described the symptoms in detailed with my outpatient psychiatrist (Dr. Baines) in detail and brought her articles on the subject.
The insomnia makes everything worse, because if you can't sleep at all it is very hard to function, it can also result in cognitive impairment.
These days I sleep approximately 4-6 hours a night (if not more, I am so blessed). Which is more than enough for me. It makes going to sleep the next night easier, and I still struggle with sleep dysregulation (have for a long time, one of the reasons they gave me anti-psychotics [pharmakeia], which in hindsight is like giving someone morphine for a paper cut - I think that doctor got reported to the CPSO by someone else, though!)