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Science and Research

New Ways To Diagnose Sleep Disorders

The Difference Between Night Owls and Early Birds

This article was originally published in the Northwestern University Feinberg School of Medicine News and Breakthroughs Podcast. It has been modified for Northwestern Medicine’s content hub, HealthBeat.

Trouble counting sheep? You’re not alone. About 70 million Americans suffer from sleep problems ranging from sleep apnea, insomnia and restless leg syndrome.

However, physicians can miss circadian rhythm sleep-wake disorders, which can cause problems with sleep. Northwestern Medicine Chief of Sleep Medicine Phyllis Zee, MD, PhD, explains, “They present like somebody who may have insomnia or somebody who may have what we call hypersomnia — excessive daytime sleepiness — but it's actually due to an alteration or pathology in the circadian clock system.”

Night Owl? Blame Your Genes

Do you ever wonder why time change or jet lag impacts your body? Your body is run by an internal clock that produces circadian rhythms, much like an internal 24-hour clock. These rhythms are generated at a molecular level. This circadian clock system exists in every single cell of the human body and is regulated by a core clock genetic mechanism.

There are more than 10 “clock genes” that determine whether you are a “night owl” or “morning lark." Dr. Zee explains, “If you're an owl, it is because your clock genetic system is taking a little slower than the 24-hour cycle. If you're a lark, [your clock] is probably going a little faster.”

Blood Test Could Pave the Way for Treatment

Northwestern Medicine is home to the first circadian medicine clinic in the country. After a diagnosis, patients can be treated with melatonin and blue light therapy.

Dr. Zee was part of a team that recently developed the first simple blood test to identify individuals' precise internal clock times as compared to external time. The test, TimeSignature, requires only two blood draws. Previously, measurements this precise could only be achieved through a costly and timely process of taking samples every hour over a span of multiple hours.

"TimeSignature is really a major breakthrough for my field and perhaps the first type of blood test that will have implications for how we treat and identify patients with sleep and circadian disorders," says Dr. Zee.

The blood test could advance personalized medicine and help physicians determine the best time of the day for a person to take certain medications, such as blood pressure medication, and other medications that target "clock genes."

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