Environmental causes are the most common of all the causes because they are a part of people's everyday life or changes in a regular daily routine. .
Depression and anxiety which fall under the category of psychiatric disorder is very common especially for those who have insomnia of all types. Worrying too often is also a main contributor as to why people have a difficult time sleeping or falling asleep. Another contributing factor to having a bad nights rest is night shift work. By working at night instead of the day you change your natural internal clock or sleep pattern that is designed to rest during the night. Having a certain sleep schedule is very important because it can tell you if you're getting enough sleep or not. No one knows your body as well as you do and if you know that you work better with a lot of sleep and go to bed at the same time every night, it will help you sleep better during the night. You will then wake up easier and refreshed the next morning. As you age it is more common for a person to develop a sleeping disorder, it is also something that you cannot always avoid. "Most people over the age of 65 have a sleeping disorder of some sort" (Webmd). Older people are also very light sleepers since they have a harder time falling asleep and it's easier for them to wake up as well. Other causes of sleeping disorders which can be common and can happen to anybody are "Colds, allergies, depression, high blood pressure and asthma" (WebMD). By having a cold or having allergies makes it more difficult to fall asleep because it may be harder to breathe especially for those who have Sleep Apnea.
There are many different sleeping disorders that have diffrent effects on people. Without quality sleep it becomes hard for the brain to function effectively. One common effect that comes with little or no sleep is hallucinations; hallucinations can come about after very long periods of time without sleep.