Sleep disorders can have many causes and are a common problem affecting millions of people worldwide. This article discusses the main causes of sleep disorders. Stress and anxiety Stress and anxiety are common triggers of sleep disorders. When a person is stressed or anxious, their body can go into a state of heightened alert, making it harder to fall asleep and stay asleep. A stressed mind can also cause a person to constantly think and worry about their problems instead of relaxing and calming down. Depression Depression can also cause sleep disorders. People who suffer from depression may have difficulty falling asleep or staying asleep and may also feel very tired and exhausted during the day.