What is insomnia?

Chronic insomnia is a sleep disorder that is associated with difficulty falling asleep, staying asleep, and/or waking up too early.

Beyond this general definition, there are a few important aspects of insomnia that I believe are important for people to know.

First, insomnia is not just a nighttime disorder. It is a 24-hour problem because people have trouble sleeping during the night, and feel exhausted and tired throughout the day. During the day, they may be excessive worried about not getting enough sleep and change how they behave to try and get more sleep or conserve energy.

Second, insomnia is a disorder of fatigue, not sleepiness. What I mean by this is that people with insomnia typically feel very exhausted; however, if you asked them to try and sleep, they probably would not be able to. People with insomnia definitely want sleep, but this wish is usually not granted – at least not in a very refreshing way.

Finally, insomnia is a subjective disorder. This is an interesting concept – there are many people out there whose sleep is objectively terrible. They may take an hour or two to fall asleep and wake up feeling crappy. However, the important part is that these people do not worry about their sleep. When we are not particularly worried about their sleep, then it would not be considered an insomnia disorder. On the other hand, there have been many people who I have worked with that has had objectively decent sleep. Save for a couple poor nights, their sleep was generally stable from a data-driven perspective. In these cases, there was usually strong beliefs about how much better their sleep could be and how much sleep affects their day to day.

Acute and Chronic Insomnia

When we think about insomnia, we need to distinguish between acute (short-term) and chronic (long-term) insomnia.

This is because how we deal with these types of insomnia can be different depending on which one it is.

Acute insomnia is a short-term sleep problem that results from stress. For example, studying for an exam, having a work presentation, losing a romantic relationship, or having a baby. In all these cases, our sleep takes a turn for the worse.

This is a completely normal response and is no cause for alarm. Usually, once you get through the exam or the work presentation, your sleep should return to normal. Acute insomnia usually lasts for a few weeks to a couple months in duration.

On the other hand, chronic insomnia typically lasts at least 3 months. The problem with chronic insomnia is that it persists even after the stressor is long gone. This is because the sleep problem has taken life of itself because of certain worries or behaviours that affect sleep. When these problems cause distress or affect you in the daytime, then intervention is needed.

Prevalence of insomnia

Insomnia is a very prevalent sleep problem. The specific rates depend on how we define insomnia. A study by Ohayon (2002) found that about a third of the population experience at least one symptom of insomnia: difficulty falling asleep, staying asleep, or waking up too early. Morin and colleagues (2011) found that 1 in 5 adult Canadians were dissatisfied with their sleep and 13% met criteria for insomnia disorder. The impact of insomnia is seen in increased accidents, loss of work productivity, and absences. Along with medical costs, insomnia is a billion-dollar industry.

How is insomnia diagnosed

As you can see, there is a difference between experiencing insomnia symptoms and meeting diagnostic criteria for insomnia disorder.

We typically follow the criteria set by the Diagnostic and Statistical Manual of Mental Disorders (5th Edition) in our semi-structured interviews to diagnose insomnia.

In order to meet diagnostic criteria for insomnia disorder, you must experience:

  • Difficulty falling asleep, staying asleep, and/or waking up too early
  • These symptoms must have last at least 3 months, for at least 3 days per week
  • These symptoms must occur even when you have enough time to sleep
  • These symptoms must cause distress or cause daytime impairment (e.g., mood, irritability, loss of concentration, memory problems, loss of productivity)
  • The insomnia must not be caused by another medical or psychiatric condition, or the because of some type of substance use

Sleep data associated with insomnia symptoms  

As discussed before, insomnia symptoms are subjective – for example, there is no necessary upper or lower limit that a person must take to fall asleep in order to be diagnosed.

However, in behavioural sleep science, there are a few cut-offs we typically use to differentiate between good and poor sleepers.

Falling asleep: On average, good sleepers take anywhere between 10-30 minutes to fall asleep. People with insomnia typically take over 30 minutes to fall asleep. Note that this is an average: even good sleepers sometimes have bad nights.

Staying asleep. Everybody wakes up in the middle of the night. Typically, we remember 2 or 3 times that we woke up and fall back asleep within a few minutes. People with insomnia are awake on average 30 minutes or more per night.

Waking up too early. People with insomnia may have a pattern of waking up a few hours earlier than they normally would. For example, if you typically sleep at 11pm and wake up 7am, then sudden awakenings at 4:00am may be indicative of insomnia. For morning birds that sleep at 9:00pm and wake up at 4:00am, this is not necessarily early morning insomnia (because they already slept 7 hours and their body simply prefers rising early).

The causes of chronic insomnia

Surprisingly, the behavioural model of insomnia suggests that there really are 3 primary causes of insomnia. These principles are used to great success in cognitive behavioural therapy.

1. Low sleep pressure. People with insomnia engage in behaviours that affect their ability to strengthen their pressure to sleep. This is important because our sleep pressure is directly related to the deep, refreshing sleep we get. However, because people with insomnia are so exhausted, they may unintentionally sabotage their build-up of sleep pressure. For example, cancelling plans, sleeping in, lying in bed, reducing physical activity, napping, and going to bed early.

2. Irregular circadian input. Our internal clock (circadian rhythm) operates on an approximately 24-hour cycle. It tells us when we should be sleepy and when we should be more awake. However, the circadian rhythm requires proper input to regulate effectively. If we are very irregular in our routines, this can create symptoms similar to jet lag. The best way to properly regulate our internal clock is by waking up at the same time every day and getting sunlight exposure as soon as possible upon waking up.

3. Hyperarousal / conditioned arousal. When we are anxious about our sleep, our body is in a constant fight-or-flight mode. This hyperarousal suppresses our ability to notice that we are sleepy and over time, can lead to an association between the bed and wakefulness. When we spend a lot of time in bed distressed and worried, the bed becomes a place of worry and distress. This is why a lot of people with insomnia report going to bed feeling sleepy but then feel wide awake when their head hits the pillow.


There are many disorders that are comorbid with insomnia. Some include:

  • Depression
  • Chronic pain
  • Anxiety
  • Schizophrenia
  • Chronic fatigue syndrome
  • Sleep apnea
  • Obsessive compulsive disorder
  • Post-traumatic stress disorder
  • Many other psychiatric and medical conditions

Differential diagnosis for insomnia

There are a few disorders that look like insomnia, but may be the result of something else.

Delayed Sleep Onset Disorder. Delayed sleep onset disorder is a disorder in which the person’s internal clock prefers to sleep and wake up late (e.g., 4am to noon). This can be problematic in regular society because people tend to wake up early. Delayed sleep onset disorder can look like insomnia because these people will typically have trouble following a regular schedule (their body does not prefer to sleep earlier). This can manifest as a difficulty falling asleep, but the problem isn’t insomnia-related. It’s a circadian clock issue.

Sleep apnea. Sleep apnea can also seem very similar to insomnia because it can cause exhaustion during the day. In this case, there may be less issue with sleeping, because people with sleep apnea may be excessively sleepy. This is because sleep apnea causes breathing disruptions that lead to many awakenings in the middle of the night. The lack of deep sleep can lead to sleep deprivation and increase risk of accidents. If you experience these issues, and notice breathing disruptions or loud snoring, then a sleep study is recommended.

Restless legs syndrome (RLS) / periodic limb movement disorder (PLMD). RLS is a type of sleep disorder in which a person notices a feeling of tingling and a need to move their legs in the evening. This can lead to difficulty falling asleep. PLMD causes jerking and twitching of limbs when a person is sleeping and can also disrupt sleep.

Evidence-based treatments of chronic insomnia

There are two main treatments of chronic insomnia that have received significant research to support their efficacy: cognitive behavioural therapy and sleep medication.

CBT for insomnia include strategies such as sleep restriction therapy, stimulus control, relaxation techniques, and cognitive restructuring to target excessive worries about sleep and leverage our sleep systems to get the deep sleep we need. CBT for insomnia is an effective long-term solution because it restores our confidence in producing high quality sleep. Compared to medication, CBT for insomnia requires more effort on the patient’s part and takes time to see results. There are self-help books on CBT for insomnia online and you can check with local sleep specialists to see if any of them provide CBT for insomnia.

Sleep medication, such as hypnotics and sedatives, are short-term solutions for insomnia. They are usually better to improve sleep in the short-term compared to CBT for insomnia. However, they may be less durable in the long-term because they only treat insomnia symptoms and don’t target the causes of insomnia. Moreover, there can side effects to medication use and people may develop a dependence to sleep medications.

Other treatments. There is research to evaluate other types of interventions for insomnia. Examples include specialty mattresses, weighted blankets, chamomile and other sleepy teas, melatonin, and sleep hygiene. There is insufficient research at this point to support these strategies in treating insomnia disorder. Specifically for melatonin and sleep hygiene, these are typically not effective and even used as a placebo in clinical trials.

I hope this post was helpful in understanding a little more about chronic insomnia / insomnia disorder!

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Best wishes,