What Is Insomnia? Causes & Symptoms Explained

Each year, 50-70 million Americans are affected by insomnia, making it the most commonly reported sleep disorder [1].

If you’ve ever dealt with insomnia, you know how incredibly frustrating it can be. Your friends may brush it off as just a simple lack of sleep, but it’s much more than that. Insomnia makes it hard to get the rest that your body needs to function properly [LINK TO SLEEP GUIDE INTRO] and can worsen your overall quality of life—you may be unable to focus at work, have less energy to exercise, or are generally more irritable.

What is insomnia?

Insomnia is a common sleep disorder characterized by the inability to fall asleep, stay asleep, or both. It affects an estimated 33 percent of adults [2], and can lead to too little sleep or poor quality sleep. In other words, when you do manage to get sleep, you may wake up too early and/or feel groggy and tired.

Symptoms of Insomnia

Though the most common symptom of insomnia is difficulty sleeping, insomnia refers to a whole host of sleep problems. Those who have insomnia may:

  • Lie awake for a long time without going to sleep
  • Wake up during the night and find it difficult to go back to sleep
  • Not feel rested when they wake up

Insomnia can also cause daytime symptoms, such as having low energy during the day, feelings of anxiety, depression, or irritability, and difficulty concentrating.

Types of insomnia

There are a few ways to categorize insomnia — by how long it lasts, whether or not it’s related to other causes, and the kind of sleep issues it causes.

  • PRIMARY VERSUS SECONDARY

Primary insomnia is a disorder not due to other medical conditions or medications. Very little is known about what causes primary insomnia and it is only diagnosed after ruling out other medical conditions.

Secondary insomnia is a symptom or side effect of another problem. Secondary insomnia can be caused by a variety of psychiatric or medical conditions, specific substances, lifestyle factors, and/or certain biological factors.

  • ACUTE VERSUS CHRONIC

Acute insomnia is common and can be brought on by situations such as stress, family pressure, or a traumatic event. Acute insomnia typically lasts a few days or weeks, but can turn into chronic insomnia if the person experiences symptoms at least three nights a week for three months or longer.

We just threw a lot of terms at you, but they’re all meant to work together to help you understand what you’re dealing with. For example, you could be having trouble sleeping for the past few weeks because you’re drinking caffeine late at night to finish an urgent work project. In this situation, you’re likely dealing with acute, secondary insomnia due to caffeine intake at night.

What Causes Insomnia?

Insomnia can be caused by a variety of psychiatric or medical conditions, specific substances, lifestyle factors, and/or certain biological factors.

MEDICAL CAUSES OF INSOMNIA

There are many medical conditions that can lead to insomnia. In some cases, the medical condition itself causes insomnia, while in other cases, symptoms of the condition or the medications used to treat the condition can make it difficult to sleep. Examples  are [3]:

  • Conditions that cause chronic pain, such as arthritis
  • Conditions that make it hard to breathe, such as nasal/sinus allergies, asthma, and heart failure
  • An overactive thyroid
  • Gastrointestinal disorders, such as heartburn
  • Stroke
  • Menopause symptoms, such as hot flashes and night sweats
  • Other sleep disorders, such as restless leg syndrome and sleep-related breathing problems

Medications that you’re taking can also affect your sleep (prescription and over-the-counter). Examples include medications taken for the common cold and nasal allergies, high blood pressure, heart disease, thyroid disease, birth control, asthma, or depression can all cause insomnia [4].

PSYCHIATRIC CAUSES OF INSOMNIA

The relationship between sleep and depression, anxiety, and other mood and mental health problems is a complicated one. According to researchers, mood disorders and sleep are intertwined [5]. Anxiety is the perfect example. You can have trouble sleeping if you feel worried, nervous, or stressed about something. But if anxiety prevents you from getting sleep on a regular basis it can cause you to become even more stressed, which then makes it harder to sleep. This can turn into a vicious cycle. Other emotional disorders that can cause insomnia include depression and posttraumatic stress disorder.

Your response to these stressful life events also matter. Research has shown that people with insomnia tend to perceive their lives as more stressful than people who didn’t have insomnia [6]. A 2014 study found that people who are mindful of their stressors had a lower risk for insomnia than those who coped with stress by watching TV, drinking, abusing drugs, and disengaging from the situation.

ENVIRONMENTAL CAUSES OF INSOMNIA

Sleep Environment

Disruptive factors such as light, noise, or extreme temperatures may make it harder for you to fall and stay asleep [7]. Try quieting your bedroom before going to bed—instead of leaving the TV on or playing music, maybe try a white noise machine.

Exposure to bright light right before bedtime makes your body think it’s daytime and suppresses production of melatonin, the hormone that regulates your sleep-wake circadian rhythm [8]. Avoiding screens, like your cellphone and laptop, 1–2 hours before bed is an important behavior change that may help you sleep better.

BIOLOGICAL CAUSES OF INSOMNIA

A warmer core body temperature

A warmer core body temp before bedtime may disrupt your ability to fall asleep. [9] Your body needs to cool down to initiate sleep, and, in good sleepers, that happens naturally at the end of the day. You can help the process by keeping your bedroom temperature cool. The National Sleep Foundation recommends a bedroom temperature of 60–67 degrees fahrenheit. [10]

Jet lag and shift work

Jet lag and shift work disrupt your body’s circadian rhythm. When you travel across time zones, your body is slow to adapt and stays on its original biological schedule. It may be worse when you fly east than when you fly west, because you “lose” time and it’s harder to go to sleep at an earlier bedtime because your circadian rhythm wants you to stay awake like you would in your home time zone [11].

If you work night shifts, rotating shifts, or even early morning shifts, this can also disrupt your circadian rhythm, since you’re regularly forcing your body to change its biological schedule. Approximately 25 to 30 percent of shift workers have symptoms of excessive sleepiness or insomnia according to the National Sleep Foundation [12].

SUBSTANCES THAT CAUSE INSOMNIA

Caffeine, nicotine, and stimulant use

You use caffeine to help you be alert, so it should come as no surprise that it can contribute to insomnia. Avoid drinking caffeine late in the day because it can take at least 6 hours to leave your system [13].

Researchers speculate that the stimulating effect of nicotine makes it hard to fall asleep, then, once you’ve fallen asleep, withdrawal from nicotine during the night makes sleep quality worse. A study published in the American College of Chest Physicians found that cigarette smokers are four times as likely to report feeling unrested after sleeping, compared to non-smokers [14].

Alcohol or other sedatives that wear off in the middle of the night

Drinking alcohol before bed may make you sleepy, but the chemical that causes sleepiness, adenosine, wears off quickly, so you end up waking up in the middle of the night [15].

If you’re having trouble falling asleep or staying asleep, you should speak with a doctor. Rory also over-the-counter melatonin supplements that may help with insomnia.


References

Sleep Statistics – Research & Treatments | American Sleep Assoc. American Sleep Association. https://www.sleepassociation.org/about-sleep/sleep-statistics/. Accessed March 25, 2019.

Bhaskar S, Hemavathy D, Prasad S. Prevalence of chronic insomnia in adult patients and its correlation with medical comorbidities. J Family Med Prime Care. 2016; 5(4):780–784

Insomnia Awareness Day facts and stats. Sleep Education. http://sleepeducation.org/news/2014/03/10/insomnia-awareness-day-facts-and-stats. Published March 10, 2014. Accessed March 12, 2019.

Know How Medications Impact Sleep – National Sleep Foundation. https://www.sleepfoundation.org/articles/how-medications-can-affect-sleep. Accessed March 25, 2019.

Soehner AM, Harvey AG. Prevalence and functional consequences of severe insomnia symptoms in mood and anxiety disorders: results from a nationally representative sample. Sleep. 2012;35(10):1367-1375.

Healey ES, Kales A, Monroe LJ, Bixler EO, Chamberlin K, Soldatos CR. Onset of insomnia: role of life-stress events. Psychosom Med. 1981;43(5):439-51.

Bjorvatn B, Waage S, Pallesen S. The association between insomnia and bedroom habits and bedroom characteristics: an exploratory cross-sectional study of a representative sample of adults. Sleep Health. 2018;4(2):188-193.

Gooley JJ, Chamberlain K, Smith KA. Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans. J Clin Endocrinol Metab. 2011;96(3):E463-72.

Morris M, Lack L, Dawson D. Sleep-onset insomniacs have delayed temperature rhythms. Sleep. 1990;13(1):1-14.

Sleep Hygiene. National Sleep Foundation. https://www.sleepfoundation.org/articles/sleep-hygiene. Accessed March 14, 2019.

Lu Z, Klein-Cardeña K, Lee S, Antonsen TM, Girvan M, Ott E. Resynchronization of circadian oscillators and the east-west asymmetry of jet-lag. Chaos. 2016;26(9):094811.

Facts about Shift Work Disorder. National Sleep Foundation. https://www.sleepfoundation.org/shift-work-disorder/what-shift-work-disorder/facts-about-shift-work-disorder. Accessed March 14, 2019.

Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med. 2013;9(11):1195-1200.

American College of Chest Physicians. Smoking Linked To Sleep Disturbances. Science Daily. February 2008. https://www.sciencedaily.com/releases/2008/02/080204172250.htm. Accessed March 25, 2019.

Wiers CE. Adenosine sheds light on the relationship between alcohol and sleep. J Neurosci. 2014;34(23):7733-7734.

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