Anxiety and insomnia disorders: What happens in your body and what can cause it?

Anxiety and insomnia often occur together. Anxiety can make it difficult to fall asleep or get enough sleep, while ongoing poor sleep can affect your mood, concentration and ability to cope with stress. The relationship can then become a cycle, but the factors behind it aren't the same for everyone (1. https://www.healthdirect.gov.au/insomnia).

Understanding what is happening in your body can make the physical symptoms of anxiety and sleep problems less mysterious. It can also help explain why treatment may involve looking at several possible factors instead of focusing on one single cause.

What happens to your body when you feel anxious?

Anxiety is part of the body's automatic response to a real or perceived threat. In the right circumstances, this can be useful because it helps prepare you to react quickly if something is dangerous.

The autonomic nervous system controls many of the automatic processes involved, including heart rate, breathing and sweating. When the brain detects a possible threat, the body's stress response can increase alertness and prepare the muscles for action.

This helps explain why anxiety symptoms can be so physical. Your heart may beat faster, your breathing can change, you might start to sweat or tremble, and your stomach can feel unsettled. Some people can also experience dizziness, a dry mouth, muscle tension, and even feelings of panic (2. https://www.healthdirect.gov.au/anxiety).

The difficulty comes when anxiety is persistent, overwhelming, out of proportion to what is actually happening, or interferes with concentration and affects sleep, work, relationships and ordinary daily life.

There is rarely one simple explanation for why this happens. Anxiety disorders are thought to involve a mixture of biological, psychological and environmental factors. Family history, stressful experiences, trauma, physical health conditions, substance use and patterns of thinking can all contribute (3. https://www.healthdirect.gov.au/anxiety).

Hormones and physical health can contribute

Hormones are chemical messengers that help regulate processes throughout the body. Changes involving hormones can sometimes affect anxiety levels or sleep.

For example, thyroid problems are among the physical health conditions that can contribute to anxiety symptoms. Hormonal changes associated with pregnancy, childbirth and menopause may also affect anxiety or sleep in some people. Menopause can cause hot flushes and night sweats that make sleeping more difficult.

But don't always assume physical symptoms have been caused by anxiety. A racing heart, poor sleep or feeling restless can also have other explanations. This is one reason a doctor may consider your physical health, medicines and other symptoms when assessing ongoing anxiety or insomnia.

How anxiety and insomnia can become connected

Insomnia is the medical term for ongoing problems falling asleep, staying asleep or getting good-quality sleep. Chronic insomnia disorder generally involves sleep difficulties at least three nights a week for at least three months, together with problems functioning during the day.

Stress and anxiety are often linked to insomnia. You might go to bed physically tired while your mind remains alert. Worrying about not sleeping can then become another source of anxiety, and these effects can then continue into the next day.

Insomnia can contribute to low energy, irritability, weight and eating disorders (4. https://pmc.ncbi.nlm.nih.gov/articles/PMC9031614/), poor memory and difficulty concentrating. Anxiety can produce some of these symptoms as well, so the two problems can overlap.

Insomnia can also have causes unrelated to anxiety. Chronic pain, sleep apnoea, restless legs syndrome, digestive or urinary problems, hormone changes and some medicines can disturb sleep. Identifying these factors can be an important part of working out what is happening.

Environmental and lifestyle factors

Sometimes your surroundings and routines associated with sleep can be part of the problem.

Noise, light and an uncomfortable bedroom temperature can disturb sleep. Shift work, travel across time zones and frequently changing sleep schedules can interfere with the body's normal sleep-wake cycle (5. https://www.nhlbi.nih.gov/health/insomnia/causes).

Caffeine can also increase anxiety and alter sleep patterns, and nicotine, alcohol and many drugs can also affect sleep. Alcohol may initially make you feel sleepy, but it can result in lighter sleep and increase the likelihood of waking during the night.

Screen use close to bedtime can also interfere with sleep patterns. Keeping regular sleeping and waking times, creating a quiet and comfortable sleeping environment, limiting caffeine, and avoiding screens before bed are all beneficial to ensure a sound night's sleep. Regular daytime physical activity may also support sleep (6. https://www.healthdirect.gov.au/insomnia).

What can be done about the contributing factors?

There's no single approach that is right for everyone because the first step depends on what is contributing to the symptoms.

Treatment for anxiety disorders may include diet or lifestyle changes, psychological therapy, or pharmaceutical or natural medicines. Cognitive behaviour therapy (CBT) is one psychological approach used to identify and change patterns of thinking and behaviour associated with anxiety (7. https://www.healthdirect.gov.au/anxiety).

Insomnia can be treated by addressing an underlying health condition, improving sleep habits and using relaxation techniques. Cognitive behaviour therapy for insomnia, usually called CBT-I, specifically addresses thoughts and behaviours that can maintain sleep problems. This can include relaxation, sleep education, changes to time spent in bed, and techniques that help reconnect going to bed with sleeping.

Medicines can also be considered for anxiety or insomnia, depending on the person's symptoms, health and circumstances, but may not be appropriate for everyone. For example, with chronic insomnia, sleeping medicines don't address the underlying problem and should generally only be considered for short-term use (8. https://www.healthdirect.gov.au/insomnia).

If anxiety or trouble sleeping is persistent, getting worse or interfering with everyday life, discussing the symptoms with a doctor can help identify possible contributors. Keeping notes about sleep patterns, anxiety symptoms, diet, caffeine and alcohol use, and medicines and other physical symptoms, can also give your clinician useful information.

Anxiety and insomnia are often connected, but neither should automatically be assumed to explain the other. Looking at psychological, hormonal, environmental and physical factors can provide a clearer picture of what may be contributing and which treatment options are appropriate for the person being assessed.