Other substances that may cause sleep problems include:
Alcohol. At first, drinking alcohol may cause sleepiness. Many people may drink alcohol to help them go to sleep. But when you drink alcohol, you are more likely to awaken later in the night.
Caffeine. Drinking a cup of coffee or other caffeine-containing beverage during the day can cause sleeplessness. Caffeine can stimulate the body for 3 to 7 hours and can interfere with your sleep as long as it remains in your body. Even the small amount of caffeine in decaffeinated beverages can interfere with sleep.
Nicotine, which can disrupt sleep and reduce total sleep time. Smokers report more daytime sleepiness and minor accidents than do nonsmokers, especially in younger age groups.