What ADHD and Insomnia Have In Common

by Eli Hendel, M.D. Medical Reviewer

Attention deficit hyperactivity disorder (ADHD) has been getting a lot of attention recently. The popularity of this trending discussion has to do with the available public data on the large numbers of children being treated with stimulants for ADHD, and the growing number of parents requesting medication as a tool to improve school work.

In the last two decades, the ADHD diagnosis has also become well-known. The National Institute of Mental Health has proposed a set of diagnostic criteria for ADHD: inattentive presentation, hyperactive/impulsive behavior, being unable to sit still, delaying or avoiding the starting and/or completion of tasks. Many of us can identify with some of these behaviors if we take an honest look at our own childhood.

My personal memories include my Russian-born grandmother dispensing her perfect solution for my “active’ behavior - one smack in the head. I “would learn,” and the problem would be solved.Being active and rambunctious, however, is not having ADHD.

Things are quite different now, decades later, with better understanding of the process involved in behaviors. Although there is no objective blood test or CT/MRI that can scientifically confirm the diagnosis of ADHD, it is a recognized medical diagnosis. Given the nature of the treatment, which typically consists of stimulant drugs, and the typical age of onset (childhood or youth) it becomes crucial to correctly identify the individuals who have this condition and who need drug therapy.** First stepsA first-step test, known as the Adult Self Report Scale** (ASRS-V1.1), is a screening test developed by the World Health Organization (WHO). This test can help to initially identify an individual who may have ADHD (the test can be viewed and downloaded from an online site).

A doctor might then administer either the Brown Attention-Deficit Disorder Rating Scale or the Test of Variables of Attention (T.O.V.A), to further screen the patient and confirm a diagnosis of ADHD. Treatment needs to be determined and adjusted based on age, desired duration of action of the medication, and other potential conditions.
Obviously the drug should work during your most productive hours, be they school or professional work time, when optimal focus and concentration are necessary. There are two main types of medications used to treat individuals with ADHD: the methylphenidate stimulants whose brand names include Ritalin, Concerta, and Focalin, and the amphetamine stimulants known by brand names like Adderall, Dexedrine, and Vyvanase.

Drug therapy: Why would you give a stimulated person a stimulant?

One wonders why the treatment for an individual who is hyperactive and cannot sit still is a stimulant drug. To answer this question one must understand the mechanism behind ADHD.

There have been many theories on the possible cause(s) of ADHD but one of the more recent theories is the “Cathecholamine Hypothesis.” Cathecholamines are substances that act in the brain to transmit signals from one nerve cell to another. Dopamine is the neurotransmitter that is deficient in key parts of the brain in someone with ADHD. Dopamine acts as a neurotransmitter involved in reward, risk taking, impulsivity and pleasure, while noradrenaline is involved in arousal and mood. For treatment of ADHD, the two classes of medications I mentioned earlier enhance dopamine levels in the brain.

The role of the thalamus

The key area of the brain thought to be underactive in a person with ADHD is called the thalamus. This structure is located in the middle of the brain, between the brainstem, which receives all the stimuli from the senses and sends the signal to the cortex, located in the outer part of the brain, where all the information is analyzed.

The thalamus is the relay station and at times can block all transmission to the cortex. This may be desirable during sleep, but it is detrimental during wake hours, especially if you’re trying to focus or be productive.

The ADHD person will typically be restless because there is a lack of stimuli coming to the cortex of the brain from all the senses (the thalamus is blocking transmissions). With this vacuum of information, the person impulsively resorts to irrational behavior. The rational of the treatment is to re-establish the communication between the thalamus and the cortex, so there is orderly processing of incoming information from the senses.

Commonalities between insomnia and ADHD

How is the brain mechanism behind ADHD similar to insomnia? One of the keys to sleeping is the ability of the brain to block the signals coming from the outside environment - allowing the brain’s activity to slow down and switch to slow brain frequency. This task, once again, falls on the thalamus. That's why the mechanism of brain dysfunction present in ADHD is also present in certain types of insomnia.

The difference is that unlike ADHD where the signals are blocked, in certain types of insomnia, the thalamus fails to block signals of the external environment during sleep. This is especially seen in individuals who suffer with chronic pain, and it can occur after certain types of strokes. There is even a genetic condition known as Fatal Familial Insomnia where this failure to block external signals occurs and leads to risk of death.

With the advent of functional MRIs, it is possible to identify the location of the breakdown of signal transmission (i.e. the thalamus) by seeing the decreased activity of the thalamus during the test.

Why is this finding significant in finding treatment?Sleeping aides target a target different parts of the brain and failures in those areas. Most tend to target the hypothalamus of the brain, which is located under the thalamus. This is where sleep is actually initiated. Different drugs treat insomnia where maintaining sleep is the issue, while other drugs treat insomnia for trouble falling asleep.

As more research is done to identify the specific part of the brain involved in a disease process, a better understanding of the necessary agents (drugs) to correct the underlying problem will be identified. Insomnias, with their different causations at play, require different sleep aids, drugs, or treatments.

So though ADHD and some types of insomnias have similar mechanisms at play, the diagnosis and treatments have great variability.

Eli Hendel, M.D.
Meet Our Writer
Eli Hendel, M.D.

Eli Hendel, M.D., is a board-certified internist/pulmonary specialist with board certification in Sleep Medicine. An Assistant Clinical Professor of Medicine at Keck-University of Southern California School of Medicine, and Qualified Medical Examiner for the State of California Department of Industrial Relations, his areas include asthma, COPD, sleep disorders, obstructive sleep apnea, and occupational lung diseases. Favorite hobby? Playing jazz music.