The History

An HCP may ask a lot of questions and may also want to collect information from your bed partner or others living in the household to better understand why you are in front of them.¹ Don’t be surprised that the questions asked are not only about you, but may also be about family members. Understanding if any similar or related issues are present in your family can be helpful, as some conditions can have a familial relationship. 

Now, what are they going to ask about you? Well, of course, questions about when you are “trying” to sleep, but also about your waking hours, including questions about diet, exercise, the use of caffeine, alcohol, nicotine, cannabis, or any illicit substances. Any other medical problems and how they are being treated can be important to know as well. And don’t blush, but they may even ask about your sex life. Shocking, we know, but there is critical relevance to your overall sleep and circadian health, as sleep problems can influence sexual performance, ability, and desire, and research suggests that sex health can impact sleep health. We weren’t joking when we said sleep and circadian science is related to everything. 

The presenting symptom of a sleep disorder or chief complaint (the symptom that leads the person to talk with their HCP) varies, and even for the same chief complaint, there can be multiple different potential causes that need to be considered. For instance, excessive daytime sleepiness (EDS) can be due to things like inadequate sleep, impaired quality of sleep, a hypersomnolence disorder, or abnormal timing of sleep. Although the most common cause of EDS is not getting enough (insufficient) sleep, it would be a disaster if the other potential causes were not considered or asked about, and the right diagnosis is missed. Unfortunately, this can and does happen and is a reason why a condition like narcolepsy can have a delay of diagnosis of 1-2 decades! 

Other medical, neurologic, and psychiatric health conditions are critical to consider when evaluating sleep and circadian health. However, sometimes the history taking and response can feel disconnected from why you went to an appointment in the first place. For instance, “I didn’t say anything about my sleep or being sleepy. I went to the heart doctor because I had a heart rhythm problem called atrial fibrillation, and the next thing I know, I am being asked sleep questions and getting a sleep study.” When this disconnect happens, you may be tempted to deprioritize these sleep-related questions and tests. In reality, the presence of another medical, neurologic, or psychiatric disorder itself or its related treatment can have a major influence on your sleep and circadian health. The presence of these factors by themselves may demand the need for a sleep evaluation and testing without you even being aware that you are experiencing symptoms or consequences of a sleep or circadian disorder. Sometimes, the main reason you have a medical disorder is due to your sleep or circadian problems; in that case, treatment of your medical disorder may not provide any benefit to what is actually your primary concern. This is part of the reason WSCN exists. To bridge the gap between day and night so that you can be empowered and live more optimally. 

Symptom Diary 

Being able to live empowered means needing to know yourself best. A symptom diary is an important tool to help you get there. In addition, it gives you a starting place to not only assist in making the diagnosis and characterizing any other related symptoms, but also monitor progress related to treatment. 

The format of a symptom diary typically includes all 24 hours and generally is done for 1-2 weeks. This includes not only jotting down the time that you lie down to sleep, how long it takes to fall asleep, and the time you wake up, but also the number of times you wake up throughout the night (and how long it takes you to go back to sleep and what you do during that time); the presence and length of any daytime naps; and symptoms or other factors that you experience while you are awake or that may be interfering with sleep. Consider including things like your mood and stress levels, and also any external factors that can be overlooked, such as a new puppy who is being housebroken. Although cute, that little fur ball can definitely worsen a sleep problem. The point is that by recording enough detail, you can identify and personalize your particular patterns, trends, and associated disability or difficulty. This results in a recipe for the right diagnosis and personalized treatment plan. There are over 70 recognized sleep-wake or circadian rhythm disorders (SWCRD), and often a person who has one disorder may actually have more than one. Therefore, these details matter. 

Prior to getting into testing that can help with the diagnosis of a SWCRD, it is important to know that many diagnoses are based on history alone. In addition, even certain conditions like narcolepsy type 1 (NT1, also called narcolepsy with cataplexy) that are typically diagnosed with sleep tests or a lumbar puncture have the possibility of being diagnosed with the history alone, based on the Diagnostic and Statistical Manual-5. 

Actigraphy

Today’s fitness trackers are based on the work of researchers who developed devices to measure and monitor sleep via a wrist- or ankle-worn “watch.” The medical devices, called actigraphs, measure rest and activity via an accelerometer over a week or two, storing the data for later download and assessment via proprietary algorithms. Actigraphy is most useful when used in combination with sleep diaries to assess sleep-wake patterns and to best understand the patterns observed. Actigraphy provides useful information that can assist in the diagnosis of SWCRD, hypersomnolence disorders like idiopathic hypersomnia (IH), and insufficient sleep.²

Laboratory Tests

The type of laboratory tests that an HCP will order depends on your particular symptoms and disorder of concern. Sometimes the testing is for risk stratification or identification of particular issues that can contribute to having a disorder, such as low iron and restless legs syndrome (RLS). If an HCP diagnoses RLS based on clinical symptoms, they will usually have blood drawn to evaluate a ferritin level and iron panel, which includes iron level, transferrin saturation, and total iron binding capacity.^3,4 If an HCP thinks that the RLS is related to another condition (that is, secondary RLS), they may order additional blood tests like thyroid testing.

Other times, laboratory testing may be performed as part of standard protocols. Guidelines indicate that a drug screen should be performed before a Multiple Sleep Latency Test (MSLT) is conducted, as certain substances can cause a false positive or negative result. Finally, there is limited laboratory testing that can be diagnostic of a condition. One special type of laboratory test is analysis of cerebrospinal fluid (CSF)—the fluid that bathes the brain and spinal cord. A lumbar puncture (spinal tap) can be performed, and the CSF checked for orexin (or hypocretin-1) level. The diagnosis of NT1 can be made if the orexin level is deficient or absent, but this test is not required to make the diagnosis; however, assessing levels of orexin in the CSF can help to establish the diagnosis or NT1.⁵ 

Genetic testing may be used when there is a concern of a genetic disorder contributing to or causing the SWCRD. 

Imaging and other diagnostic testing

Imaging studies, such as X-rays, magnetic resonance imaging (MRI), or computed tomography (CT), are not routinely used in the diagnosis or treatment of sleep disorders. In pediatrics, concerns for obstructive sleep apnea(OSA) commonly result in seeing the ear, nose, and throat specialist. If there is a concern about the need to address tonsils and adenoids, X-rays may be used to evaluate the airway impact. Similarly, in adults with concerns of sinus disease or a deviated septum, imaging may be used. 

However, if the symptoms of a SWCRD are thought to be secondary or due to another diagnosis, then imaging will be used. For instance, the presence of central sleep apnea may prompt the need for an MRI of the brain or other blood work or heart imaging to determine if there is a cause related to another organ system. 

The value of imaging as part of the characterization of the SWCRD is not clinically used at this time. Studies are ongoing to evaluate imaging to see the effects of sleep restriction and sleep disorders on the brain.⁶

Polysomnography

Standard overnight attended polysomnography is conducted in a sleep laboratory and is monitored by a technologist (hence the word, attended). This is often what people think of or call a sleep study. A technologist attaches multiple sticky patches and belts (sensors) to measure eye movements (EOG or electrooculography), brain waves (EEG or electroencephalography), chin and leg movements (EMG or electromyography), chest and abdominal movements, and position. They will also place a cannula under the nose to measure airflow and a device clamped onto the finger to measure the oxygen levels in the blood (oxygen saturation). Taken together, these patches, belts, etc., are called channels. The technologist will monitor the sleep study from outside the room via a video feed. 

Standard overnight polysomnography is routinely used to evaluate for the diagnosis of all types of sleep apnea and concerns of parasomnias that may have an abrupt onset, are increasing in frequency, or include concerns about dream enactment behavior. Polysomnography can identify and characterize other sleep-related movement disorders. A polysomnogram is also a part of the evaluation of the central disorders of hypersomnolence (CDoH), including NT1, narcolepsy type 2 (NT2), and IH, and will precede the next day’s MSLT. This combo testing may also be used when there is a concern for Kleine-Levin syndrome, but, in that case, it is used primarily to exclude other conditions. It may also be used in other SWCRD.^7-10

Home sleep apnea testing (HSAT), as its name implies, is a test that takes place in the home. This testing uses fewer channels and is only approved or indicated for the diagnosis of OSA. HSAT typically includes measurements of airflow, chest and abdominal movement, and oxygen saturation but does not measure actual sleep because it doesn’t include measurement of brain waves. HSAT must be ordered by a physician. The data from the channels are captured on the device and downloaded later for analysis.¹⁰

A 24-hour polysomnogram is conducted over 24 hours.^12,13 This longer version of a standard overnight polysomnogram frequently has the respiratory monitoring component removed because this type of study is not evaluating for sleep apnea. This test can be used (particularly in research settings) to evaluate sleep and wake periods and has the potential to identify and characterize the patterns of people living with a CDoH. These studies are not commonly used in the United States. In other parts of the world, like France and Italy, there are prolonged protocols that can last up to 84 hours to improve the likelihood of identifying CDoH. 

The MSLT is designed to measure sleepiness, or more accurately, the likelihood of someone to inappropriately fall asleep. In other words, does someone have an appropriate degree of wakefulness? The MSLT measures how quickly a person falls asleep. The test takes place in a quiet, dimly lit, temperature-controlled room and can be used to diagnose sleep disorders, usually the CDoH, and evaluate response to treatment.

The MSLT should be performed the day after a nighttime attended in-laboratory polysomnogram (which must include at least 6 hours of recorded sleep time to improve the reliability of the MSLT results). Between the 4 or 5 daytime nap opportunities, the person being tested must stay awake. The test measures how long it takes a person to fall asleep (sleep latency) and the presence and number of sleep-onset REM periods (SOREMPS). Although this test is frequently used for the diagnosis of NT1, NT2, and IH,¹⁴ the sensitivity or likelihood of diagnosing across these conditions highly varies, and the clinician should carefully take into consideration the pattern seen on these tests in combination with the history obtained.

The Maintenance of Wakefulness Test (MWT) measures a person’s ability to stay awake and, when used, is typically used to determine the effectiveness or resolution of EDS. The MWT does not require a polysomnogram the night before daytime testing. The MWT is often used to evaluate sleepiness for commercial drivers or pilots–people who are in jobs where sleepiness impacting safety is a major concern. The MWT gives an objective measure that may provide guidance on the severity of EDS and potential impact on reaction time and safety.

This test measures how long a person is able to stay awake in a dimly lit room while sitting in a recumbent position. The two accepted protocols, a 20-minute and 40-minute protocol, include four opportunities of the designated time spaced two hours apart.¹⁴

For more information on how these tools are used in the diagnosis of specific sleep disorders, check out the Sleep Disorders section.

References

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2. Smith MT, McCrae CS, Cheung J, et al. Use of actigraphy for the evaluation of sleep disorders and circadian rhythm sleep-wake disorders: an American Academy of Sleep Medicine clinical practice guideline. J Clin Sleep Med. 2018;14(7):1231-1237.
3. Silber MH, Buchfuhrer MJ, Earley CJ, et al. The management of restless legs syndrome: an updated algorithm. Mayo Clin Proc. 2021;96(7):1921-1937.
4. Handjiev S, Nobes J, Murphy MJ. “Tired all the time”: what general practitioners request and find in patients with tiredness/fatigue – an audit against NICE clinical knowledge summary of tiredness/fatigue in adults. Ann Clin Biochem. 2025:45632251329175. doi: 10.1177/00045632251329175. Epub ahead of print
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11. Park SI, Choi W, Lee C, Kim HY, Jung YG. CPAP titration pressure in split-night, full-night, and home auto-titration: a prospective comparative analysis of patients with moderate to severe obstructive sleep apnea. Nat Sci Sleep. 2025;17:401-412.
12. Biscarini F, Vandi S, Zenesini C, et al. Use of portable 24-hour polysomnography as alternative diagnostic tool for narcolepsy type 1 in adults and children. Neurology. 2025;104(7):e213473.
13. Honda M, Kimura S, Sasaki K, Wada M, Ito W. Evaluation of pathological sleepiness by Multiple Sleep Latency Test and 24-hour polysomnography in patients suspected of idiopathic hypersomnia. Psychiatry Clin Neurosci. 2021;75(4):149-151.
14. Krahn LE, Arand DL, Avidan AY, et al. Recommended protocols for the Multiple Sleep Latency Test and Maintenance of Wakefulness Test in adults: guidance from the American Academy of Sleep Medicine. J Clin Sleep Med. 2021;17(12):2489-2498.