Insomnia is a sleep disorder that affects up to 35% of adults. It is characterized by problems falling asleep and staying asleep through the night and falling asleep as long as you like in the morning. It can have dangerous effects, leading to excessive daytime sleepiness, an increased risk of motor vehicle accidents, and widespread health effects of sleep deprivation.
Common causes of insomnia include stress, irregular sleep schedules, poor sleep habits, mental health disorders such as anxiety and depression, physical illness and pain, medications, neurological problems, and certain sleep disorders. For many people, a combination of these factors can start and worsen insomnia.
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Is all insomnia the same?
Not all insomnia is the same. People can experience the condition in different ways 1. Short-term insomnia occurs only over a short period while chronic insomnia lasts for three months or more. For some people, the primary problem is falling asleep (the onset of sleep) while others struggle with staying asleep (maintaining sleep).
How a person is affected by insomnia can vary greatly based on its cause, its severity, and how it is affected by underlying health conditions.
What are the common causes of insomnia?
There are many potential causes of insomnia, and in many cases, multiple factors can be involved. Lack of sleep can also trigger or exacerbate other health conditions, creating a complex chain of causes and consequences for insomnia.
On a global level, insomnia is thought to be caused by a state of hyperawakening 2 that disrupts falling or staying asleep. Hypertension can be both mental and physical, and it can be caused by a range of conditions and health problems.
Insomnia and stress
Stress can trigger a reaction deep in the body 3 that poses a challenge to good sleep. This stress response can come from work, school, and social relationships. Exposure to traumatic situations can lead to chronic stress, including post-traumatic stress disorder (PTSD).
The body's physical response to stress contributes to hyperarousal, and stress can have the same effect. The inability to sleep in and of itself can become a source of stress, making it more difficult to break the cycle of stress and insomnia.
Researchers believe that some individuals are more susceptible to sleep problems caused by stress. These people are considered to have an "high sleep reactivity" 4 linked to other problems that affect their sleep and their physical and mental health.
Insomnia and irregular sleep schedules
In a perfect world, the body's internal clock, known as its circadian rhythm, would closely follow the circadian pattern of day and night. In fact, many people have sleep schedules that cause an imbalance in their circadian rhythm.
Two well-known examples are jet lag and shift work. Jet lag disturbs sleep because a person's body cannot adapt to the rapid change in time zone. Shift work requires a person to work all night and sleep during the day. Both can lead to disruption of the circadian rhythm and insomnia.
In some people, circadian rhythms can shift forward or backward for no apparent reason, resulting in persistent difficulties with sleep timing and overall sleep quality.
Insomnia and lifestyle
Unhealthy routines related to lifestyle, food and drink can increase a person's risk of developing insomnia.
Different lifestyle choices can cause sleep problems:
- Keeping the brain stimulated until later in the evening, such as working late, playing video games, or using other electronic devices.
- A nap in the late afternoon can throw off your sleep timing and make it difficult to fall asleep at night.
- Sleeping later to make up for the lack of sleep can overwhelm your body's internal clock and make it difficult to establish a healthy sleep schedule.
- Using your bed for activities besides sleeping can create mental associations between your bed and wakefulness.
Although often overlooked, choices about your diet can play a role in sleep problems such as insomnia.
Caffeine is a stimulant that can stay in your system for hours, making it difficult to fall asleep and possibly contributing to insomnia when used in the afternoon and evening. Nicotine is another stimulant that can negatively affect sleep.
Alcohol, a sedative that can make you sleepy, can actually worsen your sleep by disturbing your sleep cycle and causing fragmented, unrejuvenated sleep.
Heavy meals and spicy foods can be difficult for your digestion and have the potential to cause sleep problems when eaten later in the evening.
Insomnia and mental health disorders
Mental health conditions such as anxiety, depression, and bipolar disorder often lead to serious sleep problems. It is estimated that 40% of people with insomnia5 have a mental health disorder.
These conditions can induce pervasive negative thoughts and mental hyperactivity that disturb sleep. Additionally, studies show that insomnia can exacerbate mood and anxiety disorders6, making symptoms worse and even increasing the risk of suicide in depressed people.
Insomnia, physical illness and pain
Almost any condition that causes pain can disrupt sleep 5 by making it more difficult to lie comfortably in bed. Holding on to pain during insomnia in bed can amplify it, adding to stress and sleep problems 8. If you suffer from pain while lying in bed, it is important to choose the best mattress for your needs, as beds that provide good pressure relief can relieve annoying pain points .
Health complications related to type 2 diabetes can be part of the underlying cause of insomnia. Pain from peripheral neuropathy, a frequent need to hydrate and urinate, and rapid changes in blood sugar can interrupt sleep. There is also a connection between diabetes and other health conditions that are known to interfere with sleep including obstructive sleep apnea (OSA) and depression.
Other types of physical ailments, including those affecting the respiratory or nervous system, may pose challenges to sleep that can culminate in short-term or chronic insomnia.
Insomnia and medication
Sleep problems and insomnia can be side effects of many types of medications. Examples include blood pressure medications, anti-asthma medications, and antidepressants. Other drugs may cause daytime drowsiness that can affect a person's sleep schedule.
It's not just medication that can disrupt sleep. When someone stops taking the drug, withdrawal or other aspects of the body's reaction can lead to difficulties sleeping.
Insomnia and nervous problems
Problems affecting the brain, including neurodegenerative and neurodevelopmental disorders, have been found to be associated with a higher risk of insomnia.
Neurodegenerative disorders, such as dementia and Alzheimer's dementia, can throw off a person's circadian rhythm and perceive the circadian signals that drive the sleep-wake cycle. Nighttime confusion can further deteriorate sleep quality.
Neurodevelopmental disorders, such as attention deficit hyperactivity disorder (ADHD), can cause hyperexcitability, making it difficult for people to get the sleep they need. Sleep problems are common in children with autism spectrum disorder 14 (ASD) and may persist into adulthood.
Insomnia and specific sleep disturbances
Specific sleep disturbances can be a cause of insomnia. Obstructive sleep apnea, which causes many periods of breathing and temporary interruptions in sleep, affects up to 20% of people15 and can be a primary factor causing insomnia and daytime sleepiness.
Restless leg syndrome (RLS) detracts from sleep by causing a strong urge to move the legs. Abnormal behaviors during sleep, known as parasomnia, can interfere with sleep. Some well-known examples of parasomnia include sleepwalking, nightmares, and sleep paralysis.
What are the causes of insomnia in the elderly?
Insomnia occurs in 30-48% of 16-year-olds, who often have particular difficulty maintaining sleep.
As with younger people, stress, physical illness, mental health problems, and poor sleep habits can cause insomnia in older adults. However, older adults are often more sensitive to these causes due to higher levels of chronic health conditions, social isolation, and increased use of multiple prescription drugs that may affect sleep.
Research indicates that people over the age of 60 have lower sleep efficiency. They spend less time in deep sleep and REM sleep, which makes it easy to disturb their sleep 17 . Decreased exposure to daylight and reduced environmental cues for sleep and wakefulness can affect circadian rhythm, especially for older adults in managed care settings.
What are the causes of insomnia in adolescents?
It is estimated that insomnia affects up to 23.8% of adolescents18. Biological changes push adolescents toward a late “night owl” sleep schedule19, but they usually cannot sleep as long as they would like in the morning due to school start times20.
Teens may be particularly susceptible to overscheduling and stress from school, work, and social obligations. Teens also have high rates of using electronic devices in their bedrooms. Both of these factors contribute to the high rate of insomnia during adolescence.
What are the causes of insomnia during pregnancy?
Several factors can cause insomnia during pregnancy:
- Discomfort: Weight gain and change in body composition can affect posture and bed rest.
- Breathing disorder: The growth of the uterus puts pressure on the lungs, potentially causing breathing problems during sleep. Hormonal changes can increase snoring and the risk of central sleep apnea, which involves short periods of breathing.
- Reflux: Slow digestion can cause gastroesophageal reflux in the evening.
- Nocturnal urination: Frequent urination can create the need to get out of bed to go to the bathroom.
- Restless Leg Syndrome: The exact cause is unknown, but pregnant women are more likely to develop restless leg syndrome even if they had no symptoms before pregnancy.
- Studies have found that more than half of 22 pregnant women report sleep problems consistent with insomnia. In the first trimester of pregnancy, pregnant women often sleep a total of more hours, but the quality of their sleep decreases. After the first trimester, total sleep time decreases, and the most significant sleep problems occur during the third trimester.