There are a million causes of insomnia and a million ways it plays out in the nights of individual sleepers.  The most common sleep disorder, insomnia is what people mean when they say they are having trouble sleeping, or aren’t sleeping well. A more formal name is Difficulty Initiating and Maintaining Sleep (DIMS).

Insomnia can be classified along different characteristics: cause, time, and nighttime sleep patterns are the most common ways to define types of insomnia.

Primary When the insomnia is the central problem, with no other illness or obvious cause of the insomnia.
Secondary Trouble sleeping due to disease, side effects of medicine, stress, etc.



Short term or acute insomnia Lasts less than a few weeks.
Transient insomnia Adjustment insomnia - the time the body’s circadian cycle takes to adjust to changes in the environment.
Chronic insomnia Long-term insomnia. Lasts more than four weeks.



Sleep pattern  
Sleep-onset insomnia Takes a long time to get to sleep, but can sleep through the night once sleep starts
Sleep-maintenance insomnia Wakes frequently during the night and sleep is fragmented


Symptoms of insomnia include sleepiness, fatigue, decreased alertness, poor concentration, decreased performance, depression during the day and night, muscle aches and an overly emotional state (i.e. being cranky). Temporary insomnia can be brought on by stress, illness, pain, diet, medications and disruptions to circadian rhythms. More on the etiology of insomnia.

Insomnia results in a degradation in quality of life.  Bad insomnia can make a person miserable. The economic costs of insomnia to society are huge.

Chronic insomnia can be so distressing that a study found it worsened "health-related quality of life" almost as much as clinical depression and congestive heart failure.

Insomniacs suffer excessive daytime sleepiness which saps their productivity and capacity for enjoyment.  Insomniacs are more likely to be involved in automobile and industrial accidents.  Insomnia makes all the little irritations and maladies in life seem so much worse.  When you get sick, the insomnia on top of it compounds how bad you feel, and may extend the length of your illness.  Total health care costs are 60% higher for people with insomnia than for good sleepers, although it should be recognized this is not a cause-and-effect phenomenon. 

Insomnia is known to be co-morbid with mental illness.  A study found that chronic insomniacs whose insomnia was not resolved within a year had a 34% chance of developing a psychiatric disorder. For those whose insomnia disappeared, the chance was only 13%.  How the causation runs is not clear and probably not consistent from cases to case.  The insomnia could be an early symptom of the psychiatric disorder or a trigger for it, or some other relationship could be in play.

Sleep Maintenance and Sleep Onset Insomnia

Sleep maintenance insomnia is when the person cannot sleep through the night, but wakes several times for indeterminate periods.

Sleep onset insomnia is trouble falling asleep.  Sleep maintenance insomnia is trouble staying asleep.

Short periods of nighttime waking occur even in some good sleepers, but retrograde amnesia kicks in and in the morning the person does not remember waking.  These short periods that do not bother the subject do not constitute sleep maintenance insomnia.

In chronic sleep onset insomnia, when the person also has difficulty getting up in the morning, the situation can be classified as delayed sleep phase syndrome. In this case, the person's clock is off: when the body wants to sleep is not the same as when the mind wants to sleep.  More frequent and pedestrian sleep onset insomnia is just caused by having a lot on your mind or by being nervous.  Sleep onset insomnia is more common in young adults while sleep maintenance insomnia is common in the elderly. Delayed sleep phase syndrome usually strikes in adolescence, so it makes sense that young adults are more prone to sleep onset insomnia.

Sleep maintenance insomnia results in frequent and prolonged nocturnal awakenings, especially in the second half of the night.  In some sense, sleep maintenance insomnia may be an artifact of our social expectations of a night of uninterrupted sleep.  There is good evidence for a more natural pattern being a bi-phasic one and an attempt to suppress the normal mid-night waking period may lead to fragmented sleep through a longer section of the night.

What can you do about sleep maintenance insomnia?  Same as the treatments for any other insomnia – keep good sleep habits and a diary if appropriate.  Sleep restriction therapy is particularly effective for some with sleep maintenance insomnia as it forces the waking periods to be shorter and the brain to be sleepier throughout the night.  The increased sleepiness counteracts the hyperarousal that may be the cause of sleep maintenance insomnia.

Pharmaceutical companies are aware of the problem and trying to develop drugs that work for sleep maintenance insomnia.  The drugs on the market today are more effective for sleep onset insomnia.  The dosage of sleep aids is set with an aim for a full night’s sleep.  Too little and the patient is more likely to wake during the night.  Too much and the person will have morning hangover and grogginess.


See section onbdiagnosis.

How much sleep does a person need?

What to do when you have insomnia.



Treatment for insomnia can include medication and behavioral strategies.

Transient insomnia probably shouldn’t be treated at all.  The person should tough it out.  Low grade or occasional insomnia may not be worth treating with medication either.  The risks may outweigh the benefits.  And the first step for anyone having trouble sleeping is to ensure their sleep hygiene is up to snuff.  After that, if the insomnia is enough of a problem for a person, over-the-counter sleep aids, sleep restriction therapy, prescription medicine, or cognitive behavioral therapy.

Behavioral strategies include:



Both over-the-counter and prescription sleep medicines work to help people get to and stay asleep.  Like other drugs, they work more for some people than others.

Medical professionals are ambiguous about recommending or prescribing sleeping pills. Some have no reluctance, thinking of sedatives and hypnotics as technologies that are practical and safe and effective when used correctly. Others feel pills are a surrender – an admission that the underlying etiology could not be found or directly addressed. Primary insomnia – the type where the insomnia is not obviously a symptom of another condition – is frustrating for the diagnostician. Pills are a fix even if an unsatisfying one for getting to the root of the problem.

All insomnia pills have side effects. All. As with any drug, different people react differently, and sometimes the side effects are not significant compared to the benefits the patient derives. Sleeping pills on the market today are safer than the barbiturates used 50 years ago. The main side effects of modern pills are drowsiness when you don’t want to be drowsy (difficulty getting up and staying alert in the morning) and a disruption in the sleep cycle. You’ll still have all stages of the sleep cycle when you take the drug, but it may cause you to stay in stages 1 and 2 longer than healthy person with a normal sleep pattern would.

Sleepdex covers the different class of medications here.

And the most popular prescription drugs are covered in greater depth here.

Other Treatments

Therapies such as chronotherapy, phototherapy, and biofeedback are employed for insomnia.

Changing your diet can have some small effect on sleep.  We don’t put a lot of stock in stuff like acupressure, tai chi, and yoga, although some find them useful, or claim to.  This might be a placebo effect, but if it works, a placebo effect is welcome.  Herbal remedies do not have much science to support them.

Other types of insomnia

More sleep disorders.

NIH: Insomnia: Prevalence, Impact, Pathogenesis, Differential Diagnosis, and Evaluation

What happens at sleep clinics

Soundness of sleep



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