Sleep Education

American Academy of Sleep Medicine 

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Insomnia - Symptoms & Causes

Symptoms and causes of insomnia are different for every patient. Insomnia symptoms may include:

  • Fatigue
  • Problems with attention, concentration or memory (cognitive impairment)
  • Poor performance at school or work
  • Moodiness or irritability
  • Daytime sleepiness
  • Impulsiveness or aggression
  • Lack of energy or motivation
  • Errors or accidents
  • Concern or frustration about your sleep

Insomnia is most often associated with another problem. Insomnia that is not caused or worsened by other factors is rare. These factors may include:


This varies from relatively minor things like work or personal stress, to more severe changes such as death, divorce or job loss.

Other sleep disorders

Some sleep disorders can cause insomnia or make it worse. For instance, people with restless legs syndrome may have a hard time falling asleep.

Medical conditions

Many physical illnesses can cause insomnia. People who experience pain, discomfort or limited mobility from medical problems may have difficulty falling asleep or staying asleep. Insomnia due to medical conditions is most common in older adults because people tend to have more chronic health problems as they age. Conditions such as pregnancy, particularly the third trimester, and menopause can cause sleep problems. The severity and duration of insomnia often varies with the related health condition.

Mental disorders

The relationship between sleep and mental health is complex. Insomnia is sometimes caused by a mental health disorder. Often a mental health disorder will be found after a complaint of insomnia. Depression is one of the most common mental illnesses in the United States and a frequent cause of insomnia. People with depression often have trouble falling asleep or staying asleep. Difficulty falling asleep is also common in people with anxiety disorders. Other mood disorders such as bipolar disorder may also cause sleep problems.

Medication or substance use or abuse

Insomnia can be an unwanted side effect of many prescription or over-the-counter medications. Common cold and allergy medicines contain pseudoephedrine and can make it difficult to fall asleep. Antidepressants and medications to treat ADHD, high blood pressure or Parkinson’s disease can also cause insomnia.

Drinking alcohol before bedtime can cause frequent awakenings during the night. Insomnia also can occur if you suddenly stop using a sleeping pill.

Caffeine and other stimulants can prevent you from falling asleep. Stimulants also cause frequent awakenings during the night.

Some people are sensitive to certain foods and may be allergic to them. This can result in insomnia and disrupted sleep.

Environmental factors

The environment where you sleep can cause insomnia. Disruptive factors such as noise, light or extreme temperatures can interfere with sleep. Sleeping with a bed partner who snores also can cause sleep disruption. Extended exposure to environmental toxins and chemicals may prevent you from being able to fall asleep or stay asleep.

Habits or lifestyles

Irregular sleep schedules (see shift work disorder) can cause insomnia in workers who try to sleep during the day.

Updated March 4, 2015

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