Smoking cigaratte is similar to drinking coffee or energy drinks. While coffee and energy drinks contain high content of caffeine, cigarate contains high amount of nicotine, which usually stimulates and arouses your nervous system. Therefore, there's no doubt that many peolple who have trouble falling asleep (insomnia) are smokers.
According to my quick research on the internet, nicotine inside your cigarates can affect your good night sleep in various ways. Firstly, Nicotine can lead you to high blood pressure and increase in heart rate which can affect your sleep. Moreover, Nicotine is an addictive drug which can cause you to unexpectedly wake up in the middle of night.