The Search for Sleep Biomarkers

Last updated: April 19, 2019

The information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. Read our full medical disclaimer.

What is a biomarker?

A biomarker is short for Biological Marker. It refers to a broad subcategory of medical signs. They are signs of the medical state of a patient. Biomarkers are biological molecules present in the blood, other body fluids, or tissues of a patient. When a medical practitioner looks at a biomarker, they see indications of a normal or abnormal process. They might also see signs of a condition or a disease.

Unlike symptoms of a disorder, biomarkers are measurable. For example, a headache is a symptom of a disease. On the other hand, blood pressure is a biomarker and it is easy to measure.

What makes a biomarker important?

Biomarkers are vital to medicine. When a patient goes to see a doctor, the doctor runs tests on a patient. A typical test will who the patient’s x-ray results, CAT Scans, blood sugar levels, and others. These are biomarkers that one can look at to tell how the body of a person is doing.

Biomarkers are very important in developing new drugs. They are important because researchers must measure the effects of a new medication on people during clinical trials. A new drug’s efficacy is measurable by looking at the drug’s effects on biomarkers.

Biomarkers and sleep

Biomarkers are the focus of studies attempting to measure sleepiness. The problem is the difficulty in isolating a particular biomarker that corresponds only to sleepiness. For a biomarker for sleep to be effective, it needs to be completely unobtrusive and absolutely specific. This means that the biomarker needs to be specific to sleep.

Physiological measures seem to hold the most promise. Examples are measurements relating to brain activity. These include EEG, fNRI, near-infrared spectroscopy.

In general, the biochemistry of sleep is still a mystery. However, we now know of some sleep-regulatory substances. These are potential biomarkers for sleep. Other potential biomarkers of sleep include chemicals that metabolism produces.

These include IL1 and TNF cytokines. There is an association between these cytokines and Non-Rapid Eye Movement (NREM) regulation. The introduction of these cytokines can diminish an individual’s cognitive abilities. They can also enhance a person’s sensitivity to pain. These are symptoms of sleep loss. Adenosine triphosphate (ATP) is an energy molecule. They are present in the human body’s fluids and they play a role in releasing IL1 and TNF.

Interleukin-1 beta (IL1) and tumor necrosis factor alpha (TNF) are cytokines well-known for their contributions to the signaling in the peripheral immune system. Electrophysiological, molecular genetics and biochemical studies of these two demonstrates their specific effects on sleep-wake behavior. They seem to promote sleep.

Cytokines and sleep

Cytokines play a vital role in several physiological functions. This includes sleep regulation. Several cytokines have the capacity to enhance NREM sleep. Proinflammatory cytokines, in particular, are candidates for measuring sleepiness. The production of these cytokines gets enhanced through excessive food intake or contacting an infectious disease. This means that these cytokines are potentially useful as biomarkers for sleep.

However, the challenge is still finding a biomarker that is unique to sleepiness. TNF is a potential biomarker but it is also a biomarker for infectious diseases. Its use as a biomarker for sleep can be questionable since one can argue that the sleepiness measured through TNF is just a symptom of an infectious disease.

Biomarkers for sleep can give us a clearer picture of the state of insomnia as a public health problem. It can give the statistics needed to measure how insomnia and other sleep disorders affect public safety. For example, since there is no biomarker for sleep, there is no way for public safety officers to determine if a traffic incident is a result of drowsy driving. This is unlike drunk driving where we can easily check if the driver is drunk by simply measuring the driver’s blood alcohol levels.

Until now, there are still no biomarkers for sleep. They are potentially useful in coming up with a clear diagnosis of a sleep disorder. A sleep biomarker can also result in vast improvements in existing treatments for sleep disorders.

The information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. Read our full medical disclaimer.

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