Insomnia can be defined as difficulty falling asleep, staying asleep, or waking up early in the morning without being able to fall back asleep. People with insomnia may sleep less or sleep badly despite adequate sleep opportunities. Insomnia is characterized by poor or insufficient sleep, which makes it difficult to function during the daylight hours. The number of hours of sleep is not a good indicator of insomnia because people require different amounts of rest.

About 10 to 15% of adults have sleep problems that are chronic. Most people with insomnia are women and older adults.

This article describes the causes, symptoms, and diagnosis of insomnia. Separate information is available on the treatment of insomnia. See Patient Education: Insomnia Treatment (Beyond Basic).


The following symptoms are common with insomnia:

difficulty sleeping or falling asleep

Variable sleep, such as a few nights of poor sleep followed by one night of good sleep

Sleepiness or fatigue during the day


difficulty in concentrating


Reduced motivation or energy

Making mistakes or having accidents more frequently than usual

Sleep anxiety is a common problem.

Many people who suffer from insomnia also experience depression or anxiety.

Many people find that the symptoms of insomnia affect their personal relationships, work performance, and everyday functioning. Some people with insomnia have a slight reduction in their memory and ability to solve problems compared to those without insomnia. They seem to be similar in their abilities when tested for general cognitive function, verbal skills, attention, and complex thinking.

Insomniacs have a distorted sense of sleep. You may, for example, feel that you’ve not slept even though a sleep test shows you did. Even if you test less sleepy, you may feel more tired than someone without insomnia. This may be due to a problem in the “sleep arousal system” of the body, which is responsible for making you feel sleepy after a night’s rest and tired before bedtime.

It is common for people who stay awake all night to worry that they won’t perform well the next morning if they don’t get enough sleep. These thoughts can create a vicious cycle in which being awake at night causes anxiety and makes it harder to sleep.


There are many possible causes of insomnia. There are factors that can cause short-term and long-term sleeplessness.

Short-term insomnia Short-term insomnia lasts for less than three months and is often associated with stress. Stressful events can cause short-term sleeplessness.

Changes to the sleeping environment (temperature changes, light, and noise)

Loss or divorce of a loved one

Recent illness, surgery, or pain

*Use of stimulants (caffeine), medications, illegal drugs (cocaine or methamphetamine), or alcohol

Short-term insomnia often disappears once the stressor has been removed or addressed. While some changes to behavior can be made to combat short-term insomnia, like spending more time in bed or drinking alcohol to help you fall asleep, they may actually result in poor sleep, even after the stressor has been resolved.

Short-term insomnia can be caused by situations that disturb your sleep cycle. Examples of this include:

*Jet lag: Traveling between time zones may cause temporary insomnia. This is also called jet lag. Jet lag can occur in any direction but is more pronounced when traveling from west to east. It takes most people several days to adjust to the new time zone. Here are some tips on how to deal with jet lag (Table 1).

Shift Work: People working the night shift often experience insomnia. Some shift workers are sleepy while at work or driving home, but they have trouble staying asleep after noon. Sleep problems can be solved by changing to a dayshift, if that is possible, or sleeping at the same time each day, including weekends, for several weeks. The table summarizes shift work sleep disorders and other sleep time disorders (table 1).

Long-term insomnia Chronic insomnia is defined as insomnia that lasts more than three months and happens at least three times per week. Chronic insomnia increases the risk of serious medical conditions. If you’ve been experiencing insomnia for longer than three months, it is important to consult your doctor. Chronic insomnia is often associated with:

Mental health disorders such as depression, anxiety disorders, panic attacks, and posttraumatic stress disorder (PTSD).

Medical conditions such as high blood pressure, diabetes, and other disorders that cause pain or stress

Neurological disorders such as Parkinson’s disease and Alzheimer’s disease

Other sleep disorders such as sleep apnea (Beyond Basics), periodic limb movements (PLMs), and circadian rhythm disorders are also possible (see Patient Education: Adult Sleep Apnea).

Use of illegal drugs, prescription medications, caffeine, alcohol, or over-the-counter remedies (such as nasal decongestants or allergy medication)

Sleeping habits that are irregular

Chronic insomnia can occur by itself. It can sometimes be passed down through families. Infants, children, and adolescents can all suffer from chronic insomnia. The assessment of insomnia in children must also take into account information provided by the caregiver, and it is based on a less strict set of criteria than for adults.

Sleep restriction and short-duration sleep These terms are often confused with insomnia, but they mean something slightly different:

Short Sleep Requirement: People with insomnia often sleep for a very short time. Some people need less sleep and can function well after only a few short hours of sleep. People who sleep less but do not experience daytime fatigue or other symptoms during the day are often called “short-sleepers” and don’t have insomnia. You may also find that your sleep needs decrease as you age. If you need less sleep, it does not mean you have insomnia. You may also experience daytime symptoms such as fatigue or difficulty functioning.

Sleep Restrictions: People with insomnia and those who sleep less (sleep restrictions) have trouble functioning during the day. When they are given the opportunity and time to sleep, people with insomnia cannot sleep. People who have sleep restrictions will sleep quickly and normally when given the chance. Sleepiness is most often caused by chronic sleep loss, which occurs when you spend less than eight hours in bed each night.


Your health care provider may ask you about how much you sleep and whether you’ve had any problems sleeping over the course of a 24-hour period. You may need help answering these questions if you share a bed or room.

It is possible that you will be asked to maintain a sleep diary for one or two weeks. This includes recording the time in bed as well as the time actually spent sleeping.

Your provider may ask you other questions to determine the cause of your insomnia. Physical examinations can determine whether medical conditions or neurological disorders are causing your sleep issues or making them worse.

Laboratory tests are sometimes recommended to identify sleep or medical disorders. However, they are not necessary for most insomniacs. Lab tests include polysomnography or actigraphy.

Polysomnography: Polysomnography, or formal sleep studies in sleep laboratories, is a form of sleep analysis. This is a non-painful test where sensors are attached to the body in order to record your movement, brain activity, and breathing. This test is used when a sleep disorder or insomnia hasn’t responded to treatment.

*Actigraphy: Actigraphy is a method of recording activity and movements with a motion detector or monitor, which is worn around the wrist all day and night. The recording takes place over a period of one to two weeks in your home. This allows you to estimate how much and when you sleep.

Home sleep testing: This is a common test that allows patients to record their sleep while at home. Sensors are placed on the fingers and face of the patient, while a belt around the chest is used to measure oxygen levels and determine if the poor sleep was caused by the changes in breathing.


Treating the problem that is causing your insomnia, such as breathing abnormalities during sleep, may improve your sleep. Both the insomnia and associated problems may have to be treated.