What causes insomnia? This is a question many people ask themselves night after night. The answer is rarely simple, because behind insomnia there are almost always several factors affecting it simultaneously. One thing helps, however: when the causes start to take shape, the solutions also begin to be found.
In this article we go through the most common causes and background factors of insomnia. We look at the matter broadly, because insomnia is rarely the result of just a single factor. Almost always it’s a whole, involving mind, body, lifestyle, and environment.
Stress and hyperarousal
Stress is by far the most common cause of insomnia. When life is burdening, the nervous system stays in an alarm state that prevents the body from calming for sleep. Stress hormones, especially cortisol and adrenaline, disturb the natural onset of sleep.
Normally cortisol level drops in the evening, which signals to the brain that it’s time to sleep. In a stressed person cortisol stays elevated late into the evening, and the body is, as it were, stuck in “day mode.” This is called hyperarousal, and it’s one of the most common reasons why falling asleep feels impossible even though you’re exhausted.
Work stress, relationship problems, financial worries, study pressure, and life changes are typical triggers of insomnia. Importantly, the stress doesn’t have to be dramatic. Long-running mild load can accumulate gradually so that sleep is disturbed without a clear single reason.
We cover the cycle of stress and insomnia in more detail in a separate article.
Anxiety and mental health problems
Anxiety is another significant cause of insomnia. An anxious mind doesn’t know how to stop. Thoughts spin in circles, worries accumulate, and the worst possible scenarios seem most likely just when you should be falling asleep. Silence and darkness give space to anxiety, into which it gladly spreads.
The majority of people who suffer from anxiety disorders also experience insomnia. The connection runs both ways: anxiety makes sleep difficult, and poor sleep worsens anxiety. This cycle can be hard to break without conscious intervention.
Depression also disturbs sleep significantly. In depression, early waking and difficulty getting out of bed are typical. On the other hand, depression can also involve excessive sleep. Burnout also causes insomnia, because the burned-out person’s nervous system is overloaded and can’t recover normally.
Lifestyle and habits
Many daily habits affect sleep more than is generally thought. Recognizing these factors is important because they’re usually easiest to influence yourself.
Caffeine and other stimulants
Coffee, tea, energy drinks, and cola contain caffeine, which is a central nervous system stimulant. The half-life of caffeine is about 5–6 hours, which means coffee drunk at 3 p.m. still affects you at 9 p.m. In sensitive people the effect can last clearly longer. Many don’t realize the connection of caffeine to their insomnia because they’ve “always drunk coffee.” Tolerance develops to the stimulant effect, but the sleep-disturbing effect remains.
Screen time and blue light
Phone, tablet, and computer screens emit blue light, which delays melatonin secretion in the brain. Melatonin is the hormone that signals to the body that it’s time to sleep. When melatonin production is disturbed, falling asleep is delayed. This is an especially significant problem for those who scroll their phone in bed before falling asleep.
In addition to blue light, screen time has another problem: the content. Browsing social media, reading news, and checking email activate the mind exactly when it should be calming. One provocative news item or work-related message in the evening can trigger a thought cycle that keeps you awake for hours.
Alcohol
Alcohol is deceptive when it comes to insomnia. It speeds up falling asleep, which is why many use it as a “sleeping pill.” In reality, alcohol significantly weakens sleep quality. It disturbs REM sleep, causes nighttime wakings in the second half of the night, and prevents the body from recovering properly. In the morning you wake up more tired than without alcohol. Regular use of alcohol as a sleep aid can lead to growing consumption and risk of dependence.
Irregular sleep rhythm
The body’s internal clock, the circadian rhythm, works best when bedtime and wake time are regular. Weekend late nights and sleep-ins, shift work, and irregular schedules confuse the internal clock. When the brain doesn’t know when it should prepare for sleep, falling asleep becomes harder.
Sleep environment
The conditions of the bedroom affect sleep more than many believe. Too warm a room is one of the most common sleep hygiene problems. Body temperature must drop to enable falling asleep, and this doesn’t happen if the room is over 20 degrees Celsius (68°F).
Light and noise also disturb sleep. Street lights, neighbors’ sounds, and a partner’s snoring can repeatedly interrupt sleep. The quality of the mattress and pillow also affect sleep quality and the body’s ability to recover during the night.
The principles of a good sleep environment are simple: cool (16–19°C / 60–67°F), dark, quiet, and comfortable. Small changes can make a surprisingly big difference in sleep quality.
Physical causes and illnesses
Sometimes there’s a physical complaint behind insomnia that needs to be treated before sleep can return. The most common physical causes of insomnia are:
- Pain: Chronic pain such as back pain, joint pain, or migraine disturbs both falling asleep and staying asleep.
- Sleep apnea: Breathing pauses during sleep cause repeated wakings, often without the person being aware of them. The main symptom is daytime fatigue despite sufficient sleep time.
- Restless legs syndrome: Unpleasant sensations in the legs and a compelling need to move them make falling asleep difficult especially in the evening.
- Hyperthyroidism: Excessive thyroid activity speeds up metabolism and keeps the body awake.
- Menopause: Hormonal changes cause hot flashes, sweating, and other symptoms that disturb sleep.
- Frequent urination: Nighttime urination (nocturia) repeatedly interrupts sleep.
If insomnia is prolonged and no clear psychological cause is found, it’s important to see a doctor. According to clinical care guidelines, physical causes should be ruled out before treating insomnia.
Medications and substances
Many medications can disturb sleep as a side effect. Common medication groups that cause insomnia are:
- Certain antidepressants (especially activating SSRI medications)
- Beta blockers
- Corticosteroids
- Asthma medications
- Thyroid medications
If you suspect medication is causing insomnia, don’t stop the medications yourself but discuss with the doctor. Often there are alternative formulations or dosing schedules that disturb sleep less.
Learned insomnia and maintaining factors
In understanding chronic insomnia it’s important to distinguish triggering factors from maintaining factors. The trigger may be a single event, such as job loss, divorce, or illness. Maintaining factors are the habits and thinking patterns that keep insomnia going after the original cause is gone.
The most common maintaining factors are:
- Fear of insomnia: Worry about whether you’ll get sleep tonight increases tension and prevents relaxation.
- Excessive time in bed: Lying in bed without sleep weakens the connection between the bed and sleep in the brain.
- Watching the clock: Counting time at night adds anxiety.
- Daytime naps: Long or late naps reduce sleep pressure in the evening.
- Irregular sleep times: Going to bed too early or too late confuses the rhythm.
This learned insomnia is often the real problem in chronic insomnia. The good news is that learned habits can also be unlearned. Cognitive behavioral therapy for insomnia (CBT-I) is designed exactly for this purpose, and it’s research-backed effective.
You’ll find practical tips for easing insomnia in our article: What to Do When You Can’t Sleep?
Read how Aichologist can help you sleep better.
When to seek help?
Occasional insomnia doesn’t require professional help. Seek help when insomnia has continued for over a month and it disrupts your daily life. Especially when insomnia involves strong anxiety, depression, or increased substance use, professional assessment is needed.
If you need support in processing thoughts related to insomnia, try Aichologist. The AI-based conversation partner helps organize thoughts and find new perspectives on the situation.
