What is Insomnia?

What is Insomnia?

By Ryan Neely, Ph.D.

“He would lie in the bed and finally, with daylight, he would go to sleep. After all, he said to himself, it is probably only insomnia. Many must have it.”

― Ernest Hemingway, A Clean Well-Lighted Place 

No doubt you’ve heard much about the importance of sleep. Headlines about the role of sleep in health and disease are a regular occurrence, and boasts about foregoing sleep to increase productivity are increasingly being met with skepticism. Indeed, insufficient sleep is associated with a long list of health conditions including heart disease, cancer, accidents, and an overall increased risk of premature death (Chattu et al., 2018). Despite its importance, many people have the frustrating experience of trying to sleep, but not being able to. Insufficient sleep is often blamed on insomnia; however, insomnia has a specific definition in the field of sleep medicine and is not the only sleep disorder that can lead to a lack of sleep. Furthermore, insomnia itself comes in a number of unofficial “flavors,” each with its own characteristics. Although only a doctor can diagnose insomnia, this blog should help explain

  1. the defining characteristics of the condition
  2. how it is clinically diagnosed, what what it can be confused with
  3. how scientists think about insomnia in the field of sleep research

According to the American Academy of Sleep Medicine (AASM), Insomnia is the most prevalent sleep disorder in the general population with as many as 50% of adults experiencing some of the defining symptoms. As it turns out, Hemingway’s character was correct - many people do have it!

Insomnia: a technical definition

Insomnia disorder is defined in the Diagnostic and Statistical Manual of Mental Disorders, which is used to classify mental disorders in the United States and is currently in its 5th revision (DSM-V-TR). The DSM outlines symptoms that are typically associated with insomnia, as well as some criteria that must be met in order for someone experiencing these symptoms to be considered to have insomnia disorder. The primary symptoms that define insomnia are:

  • Difficulty initiating sleep, for example taking more than 30 minutes to fall asleep at the beginning of the night
  • Frequently waking up in the middle of the night, and subsequent difficulty falling back asleep
  • Waking up 30 minutes or more before the desired wake up time, when the sleeper has yet to be asleep for at least 6.5 hours

While these symptoms may happen to everyone at some point, the DSM requires that they happen at least 3 nights per week in order to be considered symptomatic of insomnia disorder. Furthermore, acute insomnia is defined as the above symptoms occurring for at least one month but less than 3 months, whereas chronic insomnia sufferers experience these symptoms for three months or more. Lastly, the DSM stresses that in insomnia disorder, these symptoms occur even when an individual has ample opportunity to sleep and that the associated lack of sleep results in some form of waking distress or impairment. This daytime stress and impairment is a key feature that distinguishes insomnia disorder from simply a poor night of sleep. 

How doctors diagnose insomnia (and similar conditions)

The AASM has issued formal guidelines for the evaluation of insomnia in adults. As you may have noticed above, the DSM-V-TR definition of insomnia is based on an individual’s own report about the symptoms they experience, the frequency of those symptoms, and the impact they have on the individual’s daily life. Therefore, practitioners facing a complaint of poor sleep will generally try to answer the following questions about a patient in order to determine whether they may be suffering from insomnia disorder. 

  1. Do the primary symptoms fit? In other words, is the patient’s sleep complaint related to an inability to fall asleep and/or stay asleep, even when they have a good opportunity to do so? Additionally, how long have these symptoms existed, and how frequently do they occur?
  2. What is the patient’s typical pre-sleep routine? This question is important because it may point to factors that are perpetuating insomnia. For example, eating, screen use, and smoking in bed may make it harder to fall asleep. Additionally, many patients experiencing insomnia develop an anxious relationship with bedtime, which paradoxically can worsen their symptoms.
  3. What is the patient’s typical sleep/wake cycle? Understanding these details can be crucial to distinguish insomnia from a Circadian Rhythm Disorder, in which an individual’s biological clock is misaligned with their desired sleep cycle. The practitioner may ask questions related to how long a patient takes to fall asleep, how frequently they wake up, how variable are their sleep/wake times, and whether waking happens spontaneously or with an alarm. 
  4. Nighttime behaviors: what the patient does while in bed can help rule out other possible conditions as well. These may be reported by the patient themselves, a bed partner, or the use of monitoring technology (either in-home or at a sleep lab). For example, snoring or gasping could indicate sleep apnea - another commonly occurring sleep disorder. Kicking or restlessness may indicate a sleep-related movement disorder, while “acting out” or vocalizing could be a sign of parasomnias.
  5. Does the patient have any existing medical conditions or medication uses that may be related to the reported sleep disturbance? Many psychiatric conditions are frequently associated with insomnia, as well as many types of medications. Additionally, environmental factors like shift work or cross-meridian travel can also contribute to sleep disturbances.
  6. Last but certainly not least, the practitioner will assess whether the patient is experiencing distress or impairment relating to their inability to sleep. The patient may be asked questions about daytime tiredness and the need for napping, mood or cognitive difficulties, and general quality of life.

Insomnia in the field of sleep research

While clinicians treating insomnia disorder have reached consensus about its symptomology, sleep researchers probing for a deeper understanding of the disease often paint a more complex picture. One common yet perplexing phenomenon is that of sleep state misperception. Often, individuals reporting insomnia symptoms undergo examination in a sleep lab, during which time their brain activity, eye movements, cardiovascular function, and body motion (among other things) are continuously monitored (not unlike the parameters recorded by Elemind Sleep!). During these sessions, some individuals report lying awake for long periods of time and frequent awakenings; however, their brain may show all of the signs of falling asleep quickly and remaining asleep for most of the night (Valko et al., 2021). Although researchers do not yet understand what accounts for these discrepancies, some have argued that this presentation should be classified as a unique subtype of insomnia disorder (Edinger & Krystal, 2003).

Complicating this picture further, a recent series of studies analyzing 34 traits across 4322 individuals determined that there were likely 5 distinct subtypes of insomnia, each with unique characteristics and response to medication (Blanken et al., 2019). In fact, the International Classification of Sleep Disorders, 2nd Edition (ICSD-2) recognizes twelve subtypes of insomnia, primarily distinguished by their suspected cause (or lack thereof). Clearly, there is much to learn about the many causes of insomnia and the best way to treat it. However, it is becoming increasingly clear that a one-size-fits all approach may not be best. 


Although most everyone will experience difficulty sleeping at some point, insomnia disorder is defined as a frequent inability to fall and/or stay asleep that creates a negative impact on an individual’s ability to function during the day. Similar to many psychiatric disorders, insomnia is diagnosed by careful consideration of a patient’s reported experience, and by attempting to rule out other possible conditions or causes. The field of sleep science is still working to understand the underlying causes of insomnia, but a picture is emerging that suggests there may be several unique types of insomnia that likely require a personalized treatment approach. At Elemind, we engage with the top sleep scientists and clinicians to stay on top of the latest sleep research. Elemind Sleep is designed to measure and respond to your neurophysiology in real-time, personalizing your treatment at the speed of your brain. We hope that with by engaging with our community of users and research partners, we can make progress in better understanding how the brain promotes healthy sleep, and create ever-improving solutions that help our users sleep better.


Blanken, T. F., Benjamins, J. S., Borsboom, D., Vermunt, J. K., Paquola, C., Ramautar, J., Dekker, K., Stoffers, D., Wassing, R., Wei, Y., & Van Someren, E. J. W. (2019). Insomnia disorder subtypes derived from life history and traits of affect and personality. The Lancet Psychiatry, 6(2), 151–163. https://doi.org/10.1016/S2215-0366(18)30464-4

Chattu, V. K., Manzar, Md. D., Kumary, S., Burman, D., Spence, D. W., & Pandi-Perumal, S. R. (2018). The Global Problem of Insufficient Sleep and Its Serious Public Health Implications. Healthcare, 7(1), 1. https://doi.org/10.3390/healthcare7010001

Edinger, J. D., & Krystal, A. D. (2003). Subtyping primary insomnia: Is sleep state misperception a distinct clinical entity? Sleep Medicine Reviews, 7(3), 203–214. https://doi.org/10.1053/smrv.2002.0253

Valko, P. O., Hunziker, S., Graf, K., Werth, E., & Baumann, C. R. (2021). Sleep-wake misperception. A comprehensive analysis of a large sleep lab cohort. Sleep Medicine, 88, 96–103. https://doi.org/10.1016/j.sleep.2021.10.023
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