It can be associated with medical illnesses interrupting sleep associated with physical disturbance such as pain, tinnitus, general anxiety, depression, or medication. The normal sleep cycle lasts approximately 90 minutes and occurs approximately 4-6 times a night. The cycle is divided into several stages of sleep. At this stage the breathing, heartbeat and brain waves have slowed. During sleep, we experience dreams which occur in a separate stage called REM or rapid eye movement in which the breathing, heartbeat, and brain waves have increased.
Dreams range in time from a few seconds to several minutes.
After each dream the body returns to stage 2 and then proceeds through the stages of sleep again. When a person has a sleep disorder, the normal sleeping pattern is disturbed. Everyone has trouble falling or staying sleep from time to time. But if insomnia lasts for more than a month or disrupts your daily life, then medical evaluation and therapy may be indicated. Tinnitus causes insomnia by the constant awareness of the sound.