Insomnia affects roughly 40% of people with chronic medical conditions, and the cause is often something beyond stress or poor sleep habits. Dozens of medical conditions can trigger or worsen insomnia, ranging from mental health disorders and chronic pain to hormonal imbalances and medication side effects. Understanding which conditions disrupt sleep, and how they do it, can help you identify what’s actually keeping you awake.
Mental Health Conditions
Psychiatric disorders are the single most common medical cause of insomnia. Roughly 40 to 50% of people with insomnia also have a diagnosable mental health condition, and the relationship runs in both directions: poor sleep worsens anxiety and depression, which in turn makes sleep harder.
Depression often disrupts the ability to stay asleep. People with major depression frequently wake in the early morning hours and can’t fall back to sleep. Anxiety disorders tend to affect the other end of the night, making it difficult to fall asleep in the first place because of racing thoughts or physical tension. Post-traumatic stress disorder (PTSD) can cause both problems, along with nightmares that jolt people awake and leave them too activated to return to sleep. Bipolar disorder, particularly during manic or hypomanic episodes, can reduce the perceived need for sleep to just a few hours a night.
Chronic Pain Disorders
Sleep complaints show up in 67 to 88% of people with chronic pain conditions, and at least half of all people diagnosed with insomnia also live with chronic pain. This includes conditions like fibromyalgia, osteoarthritis, rheumatoid arthritis, chronic low back pain, and neuropathy.
The connection goes deeper than simply being too uncomfortable to sleep. Chronic pain increases levels of a neurotransmitter called dynorphin, which activates stress circuits in the brain. Research from the University of Arizona identified dynorphin as a key factor in how chronic pain produces insomnia. In animal studies, activating the same receptor system that dynorphin targets promoted profound wakefulness, while blocking it restored normal sleep patterns. This means chronic pain doesn’t just hurt at night; it actively rewires your brain’s arousal system to keep you awake.
Respiratory Conditions
Asthma and chronic obstructive pulmonary disease (COPD) both worsen at night and can fragment sleep significantly. The specific symptoms that wake people up include coughing, wheezing, breathlessness, and nasal congestion. People with asthma often experience their worst airway narrowing between 2 and 4 a.m., a pattern called nocturnal asthma.
Both conditions also increase the risk of obstructive sleep apnea, where the airway repeatedly collapses during sleep, causing brief awakenings that the person may not even remember. The combined effect is sleep that feels unrefreshing even after a full night in bed.
Acid Reflux and GERD
Gastroesophageal reflux disease (GERD) is one of the most overlooked causes of insomnia. In a survey of nearly 12,000 people with GERD, 89% experienced nighttime symptoms, 49% had difficulty falling asleep, and 58% had difficulty staying asleep. When you lie flat, gravity no longer keeps stomach acid in your stomach, so acid exposure during sleep tends to last longer and cause more damage to the esophagus than daytime reflux.
Some people wake up with obvious heartburn or a sour taste. Others experience only a vague sense of discomfort, chest tightness, or coughing that pulls them out of sleep without a clear cause. If you consistently wake in the middle of the night without an obvious explanation, reflux is worth considering.
Neurological Conditions
Several neurological diseases directly damage the brain regions that regulate sleep and wakefulness.
In Alzheimer’s disease, the buildup of abnormal proteins in the brain correlates with decreased deep sleep and REM sleep, increased nighttime wakefulness, and disruption of the internal body clock. Degeneration of the brain’s master clock (a small cluster of cells that tells the body when to sleep and when to be awake) is thought to be at the root of the severe circadian rhythm problems that many Alzheimer’s patients experience, including the “sundowning” agitation that peaks in the evening.
Parkinson’s disease causes insomnia through multiple pathways at once. Nighttime symptoms like muscle stiffness, pain, and frequent urination make it hard to stay asleep. Depression, which is common in Parkinson’s, adds another layer. And the dopamine-based medications used to treat movement symptoms can themselves cause sleep disturbances or sudden “sleep attacks” during the day that throw off the sleep-wake cycle.
Restless legs syndrome (RLS) deserves special mention. The irresistible urge to move the legs, which worsens at night and during rest, directly delays sleep onset. RLS is three times more common in people with multiple sclerosis and is also more prevalent in advanced Parkinson’s disease, likely because all three conditions involve disrupted dopamine signaling.
Thyroid and Hormonal Imbalances
An overactive thyroid (hyperthyroidism) accelerates nearly every system in the body. Your heart rate rises, your body temperature climbs, and your metabolism speeds up, all of which make it harder to wind down at night. Many people with hyperthyroidism describe feeling “wired but tired,” unable to relax enough to fall asleep despite being exhausted.
Cortisol imbalances also play a role. Conditions that elevate cortisol, your body’s primary stress hormone, can keep your nervous system in a state of alertness when it should be powering down. Cushing’s syndrome, chronic high-dose steroid use, and even poorly controlled diabetes (which triggers stress responses when blood sugar swings overnight) all fall into this category.
Kidney Disease and Nocturia
Chronic kidney disease (CKD) impairs the kidneys’ ability to concentrate urine and manage fluid balance, which often results in nocturia: the need to get up and urinate multiple times during the night. Reduced kidney function disrupts salt and water regulation, driving excess urine production overnight. Each trip to the bathroom resets the process of falling asleep, and for many people with CKD, the cumulative effect is severe sleep fragmentation that meets the criteria for insomnia.
Nocturia from kidney disease is different from simply drinking too much water before bed. Because the kidneys can’t efficiently reabsorb fluid during the day, the body shifts more of that work to nighttime hours, when you’re lying down and blood flow to the kidneys increases.
Medications That Cause Insomnia
Sometimes the condition itself isn’t what’s keeping you awake. The medication treating it is. Several widely prescribed drug classes list insomnia as a common side effect.
- Beta-blockers (used for high blood pressure and irregular heartbeat) suppress the body’s natural melatonin production, making it harder to fall and stay asleep.
- Certain antidepressants can be stimulating rather than sedating. Some SSRIs and other classes of antidepressants are known to disrupt sleep, which creates a frustrating cycle when the depression they’re treating also causes insomnia.
- Oral steroids like prednisone stimulate cortisol production and mimic the body’s stress response, directly disrupting the sleep cycle. People on steroid tapers often report the worst insomnia during the first few days of high doses.
- Some mood stabilizers and ADHD medications are also stimulating enough to interfere with sleep, particularly if taken later in the day.
If your insomnia started or worsened around the same time you began a new medication, that timing is worth noting. Adjusting the dose, switching to a different drug in the same class, or changing when you take it can sometimes resolve the problem without adding a sleep aid on top.
How These Conditions Overlap
In practice, insomnia rarely comes from a single source. Someone with rheumatoid arthritis may also take a corticosteroid that elevates cortisol and develop depression from living with chronic pain. All three factors independently worsen sleep. A person with COPD may take a beta-blocker for a heart condition and have GERD from the increased pressure in their abdomen. Each layer compounds the others.
This is why identifying every contributing factor matters. Treating depression alone won’t resolve insomnia if untreated acid reflux is also waking you up at 3 a.m. Addressing pain without looking at medication side effects leaves part of the problem in place. The most effective approach is working through each potential contributor rather than assuming a single diagnosis explains everything.