Hello.
First of all, you need to see how much these rare occasions are affecting your day to day life. Quite often, knowing that you can tolerate them for a while is reassuring and you might be able to overcome this. However, in todays age of specific diagnoses, you might want to see if this can be categorized into some known condition. It is difficult to point out what could be the problem, but it seems you might have to consult a Sleep Specialist for more ideas on this. It may turn out to be nothing serious, but you can definitely get some management advice.
You might have to explore some anxiety issues related to these events. Tobacco can contribute to sleep disturbances. What your experienced was probably in a transition phase of falling into sleep. And tobacco can interfere with this phase. Please consider consulting a Sleep Specialist in your area. If you are not able to find one, you may always seek your GP's help.
Hope this helps. Take care.
Abhijeet Deshmukh, MD
(This post is for the purpose of providing medical information and is not a substitute for a face-to-face consultation with a doctor. This post is not intended to give or rule out a diagnosis, create a doctor-patient relationship or replace an existing one. I am not able to diagnose medical conditions online. Please consult with your doctor or a qualified healthcare provider for diagnosis and treatment options)