Bats are nocturnal (active at night). Bats 'see' in the dark using a special skill called echolocation. Bats make noises and wait for the sound waves to bounce back off objects (an echo), if it doesn't bounce back then they can safely fly forward..
Smokers are nocturnal (sometimes), they see in dark using special skill call "smokolocation"
Smokers' minds make internal noises and wait for cigarette smoke waves to bounce back off walls, if it does bounce back then they safely become nocturnal..
First few weeks, after quitting, could not sleep. I read good articles on insomnia, nicotine withdrawals etc.
EX community had good discussions on insomnia, I remember, I had gone through those days !
The trouble of sleepless nights used to disturb next day plan, and absence of sleep caused tiredness during the day.
So, best are, not to think of smoking while going to sleep. Think something feel good factor like how I am great (!),
that I did not smoke for last few days. Feel good factor like no body odour like ash, and feel good factor of natural breathing in and breathing out. I might used to get up in the night, but then used to tell myself, calm down, calm down, it is nothing, but recalling your brain to bad nicotine. So really feel good that you do not smoke now. Brain will slowly forget. Insist feel good factor in mind !
Slowly the unwanted insomnia ran away, and I started getting better sleep (better than Smoking days) going forward.