Primary and Secondary Insomnia

sleeping personDifficulty in Initiating and Maintaining Sleep – Insomnia - is often classified by whether it is a symptom of another condition or not.

Primary insomnia is traditionally defined as difficulty sleeping that does not have a separate condition causing the loss of sleep. A person kept awake by pain from a broken bone would have secondary insomnia. The causes of secondary insomnia are legion, and include everything from alcohol and drug ingestion, to many medical and psychiatric problems.  The difference between primary and secondary insomnia depends on whether the insomnia is considered a disorder or a symptom.

The medical field has undergone a shift in attitudes toward primary insomnia over the years.  At the 1983 National Institutes of Health State-of-the-Science Conference, the consensus was that diagnoses of primary insomnia constituted "giving up".  Treatment could be administered for short-term insomnia, but for long-term insomnia the underlying cause should be found and dealt with.  All insomnia was considered secondary insomnia.

The 2005 State-of-the-Science Conference changed positions.  Now primary insomnia was considered real and worth directly addressing.  Non-drug therapies are still preferred, but now the consensus is that doctors don’t have to search for an underlying cause of the insomnia. 

Primary Insomnia

Primary insomnia is sleeplessness that cannot be attributed to some other cause. It is also called idiopathic insomnia.  An estimated 10% of the population has primary insomnia.

To be classified as primary insomnia in a clinical sense, the patient must experience difficulty in falling asleep, difficulty in staying asleep, early awakening, or non-restorative, poor quality sleep. The trouble sleeping must be associated with daytime symptoms. These can include fatigue, trouble concentrating, memory or mood disturbances, tension headaches, and other types of daytime impairments or symptoms.

The pathophysiogical mechanisms underlying primary insomnia are usually unknown, and medical practitioners address the insomnia directly. Sleep researchers believe that hyperarousal, circadian dysrhythmia, and homeostatic dysregulation underlie chronic insomnia. But as a practical matter for doctors, patients just want a good night’s sleep.

The first line of attack for primary insomnia is almost always drug-free. Good sleep hygiene is always recommended, and those suffering from sleepless nights are advised to take another look at their bed practices. Often turning down the air temperature in the room is all it takes to facilitate unbroken sleep.

You often see this statement: insomnia is not a condition; it is a symptom. This is to encourage readers (patients, health care providers, etc.) to look at the underlying cause of insomnia, which is often another illness. However, like so much in sleep, the literal validity of that statement is not so clear. Secondary insomnia is indeed considered a symptom or a side effect of other phenomena in the body, but often the insomnia itself is considered the main problem, the main thing worth attacking and treating. When the insomnia is considered an illness itself, not an effect of some other etiology, it is called primary insomnia.

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Chronic insomnia – insomnia that goes on for a month or more – is often treated as primary insomnia. Doctors attack insomnia directly (rather than an unknown underlying cause) to help the patient achieve a better quality of life. More on chronic insomnia.


Secondary Insomnia

Secondary insomnia is a result of other causes – illness, drugs (including caffeine and alcohol), excessive worrying, pain, etc. Depression is a leading cause of secondary insomnia.  If the doctor and patient can figure out the underlying condition, treating it is often more productive than attacking the insomnia directly. Another name for secondary insomnia is comorbid insomnia. Comorbidity refers to the presence of two or more disorders or diseases. Many illnesses can cause insomnia, including psychiatric problems and anything causing pain. Most cases of insomnia are comorbid insomnia.

Many depressives start sleeping much better as soon as they begin taking antidepressant medication, even though those medications have no effect on the sleep patterns of non-depressed people. Pain relief medications often produce drowsiness as a side effect. This is most obvious in the very strong opiate pain medications, and opium has been known for millennia to induce sleep. (Indeed, morphine was named after Morpheus, the god of sleep). Less strong over-the-counter pain medications are often mixed with antihistamines. A good example is Tylenol PM, which is a mixture of the pain reliever acetaminophen (the ingredient in regular Tylenol) and diphenhydramine HCl., an antihistamine that promotes sleep.

Opiate medicines such as percodan as well as OTC preparations like Tylenol PM disrupt the sleep cycle to some extent, so they are not suggested for long term treatment of insomnia. But they can effectively address sleeplessness if the patient needs pain relief medication for other reasons.

There is a growing idea among scientists that the cause-and-effect long thought for secondary insomnia is backwards.  Rather than the insomnia being a consequence of the other illness, the insomnia may be a trigger for the other illness.  What if, rather than depression causing insomnia, insomnia causes (or at least contributes to) depression?  This underscores the reality that insomnia is a brain disorder rather than a product of the mind.


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