Insomnia is a common sleep disorder defined by night time and daytime symptoms. Night time symptoms include persistent difficulties falling and / or staying asleep and / or non-restorative sleep. Daytime symptoms of insomnia can include diminished sense of well being, compromised functioning such as difficulties with concentration and memory, fatigue, concerns and worries about sleep. The diagnosis is made when the symptoms persist for at least 1 month and insomnia is considered chronic if it persists for at least 6 months. Nearly one in 10 adults in the United States suffers from insomnia.

It is important to realize that not everyone who has problems sleeping has insomnia. The word persistent is emphasized because many people occasionally experience disturbed sleep at night but their problem is transient.

The Insomnia Severity Index may help if you are uncertain that your insomnia might be severe enough to require evaluation. If you are concerned, the medical  providers at the UT Sleep Disorders Center would be happy to help with your sleep problem.

Types of Insomnia

Insomnia is most often classified by duration:

  • Transient Insomnia - Less than one month
  • Short-term Insomnia – Between one and six months
  • Chronic Insomnia – More than six months


However, insomnia can also be classified as:

Primary insomnia – Insomnia that is present with no other co-existing disease. Most of the studies on treating insomnia have been done with people who have primary insomnia.

Co-morbid insomnia – When insomnia exists in conjunction with another medical or psychiatric condition. Co-morbid insomnia does not have to be caused by or change with the co-existing disorder. Most cases of insomnia belong to this category. Sometimes, having insomnia can make the medical or psychiatric condition worse and hinder its treatment. For example, people with depression and insomnia do not respond as well to depression treatment as depressed people without insomnia.

Causes of Insomnia

In about 75 percent of people with insomnia a specific cause of their insomnia can be identified. One of the most common causes is stress related to family or work situations. Poor sleep is a common reaction to stress, but there are large individual differences in how people react to and cope with stress. These differences likely play a role in the development of insomnia.

Biological Factors:

Some health conditions can disrupt sleep, including:

  • Conditions that cause chronic pain, such as arthritis and headache disorder
  • Conditions that are associated with difficulty breathing, such as asthma, congestive heart failure, chronic obstructive pulmonary diseases, and sleep apnea
  • Depression, anxiety and other psychiatric disorders
  • Abnormal thyroid function
  • Acid reflux disorder
  • Restless legs syndrome
  • Conditions that increase urinary frequency, such as enlarged prostate
  • Dementia


Certain medications and commonly used substances can disrupt sleep. These include the following:

  • Caffeine, nicotine, and other stimulants
  • Alcohol or other sedatives that wear off in the middle of the night
  • Some asthma medications (e.g. theophylline)
  • Some decongestants and allergy and cold medicines
  • Some steroids, such as prednisone
  • Beta blockers (medicines used to treat heart conditions)


Sleep disruptions caused by medical conditions, medications and substances may resolve with treatment. However, this is not always the case and for some individuals, insomnia may persist after the medical condition is managed or resolved.

Environmental Factors:

In some cases, despite stress subsiding and medical conditions receiving treatment, insomnia can persist. Patients will find that they have trouble either falling asleep or staying asleep – and occasionally, both. Excessive light or noise, uncomfortable bedding
or having children or pets in bed with you can disrupt sleep. A bed partner's sleep or
health problem can also interfere with your sleep.

Conditioned Arousal: The bed and the bedroom become linked with wakefulness, arousal or negative emotions. The bed and the bedroom become unconscious cues for arousal rather than sleep. For example, many people with insomnia report that they doze off while watching TV or reading in the living room, but become fully awake when they go to bed. For these people, past experience with tossing and turning while trying to sleep has made the bed a cue for wakefulness rather than sleep.

Trying too hard: Some people react to poor sleep by trying harder. They extend the time they spend in bed, avoid evening activities that they used to enjoy, toss and turn in bed, and even try a "night cap." Rather than solve the problem, these strategies often make it worse. Prolonged time in bed actually promotes wakefulness. The very act of "trying" produces frustration, increases arousal and can actually cause stress. The process is like trying to get out of a Chinese finger cuff. The harder you try to pull your fingers away, the more stuck they become. When you let go, you can ease your fingers out.

Worrying: Worry about sleep is another common reaction to having difficulty sleeping. After a period of not sleeping well, you may find that you start worrying about whether you'll struggle to sleep in the coming night. Then you can begin to worry about how insufficient sleep will negatively affect you the next day. Such worries, though understandable, are counterproductive and end up making even more difficult to fall asleep.

Who is at Risk for Insomnia?

There are certain groups of people who are at increased risk for the development of insomnia in comparison to others. It has already been noted that people who are experiencing stressful situations or medical conditions such as depression or those that cause physical discomfort or pain are more at risk to developing insomnia.

Individuals who have very irregular sleep wake schedules are at risk for developing insomnia because irregular sleep-wake schedules weaken the signals from the circadian clock regulating sleep and wakefulness. Those whose jobs involve frequent time zone changes or shift work are at particularly high risk. Other groups include:

  • "Night owls" who do not have a regular wake time.
  • People who describe themselves as "worriers" are at risk for insomnia. Learning to set one's worries aside can help reduce this risk.
  • People who do not unwind from the day's stresses are more likely to sleep poorly.
  • People with other sleep disorders, such as Restless Leg Syndrome and Sleep Apnea.
  • People with genetic predisposition are also more likely to develop insomnia. While there are currently no genetic tests that can identify those at risk for insomnia, twin studies show that genetics plays a role in insomnia.
  • Women are twice as likely to experience insomnia as men.
  • Older adults are more likely to experience insomnia.

Diagnosing Insomnia

An insomnia disorder is diagnosed when the disturbed sleep lasts more than a month and negatively impacts general well being, either because it is very distressing or because it leads to impairment in performance or mood. Sleep specialists can determine if the symptoms are not better explained by other disorders, including sleep, psychiatric, or medical.

Your doctor will obtain a clinical history and may obtain additional information from questionnaires and/or objective measures to help diagnose your insomnia and rule out other sleep disorders. Some examples can include:

Sleep Diary: Your doctor may ask you to keep a sleep diary as a way to better understand your sleep patterns.

Polysomnogram: An over-night stay in the sleep laboratory is not necessary for a diagnosis of insomnia. However, sometimes a sleep study will be recommended. The most common reason for a referral to an over-night sleep study is a suspicion that another sleep disorder, such as sleep apnea or periodic limb movement disorder might be present. A sleep study is also recommended when sleep is not refreshing despite being of adequate length.

Actigraphy: a test to assess sleep-wake patterns over time. Actigraphs are small, wrist-worn devices (about the size of a wristwatch) that measure movement and light exposure.

View Treatments for Insomnia



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