Insomnia (Trouble Sleeping): Causes and What Helps

Types of sleeplessness

• Sleep-onset insomnia: lying awake for more than 30 minutes before falling asleep. Common with anxiety and delayed body clocks.
• Sleep-maintenance insomnia: waking up during the night and struggling to get back to sleep. Common with pain, needing to urinate, sleep apnea, menopause and alcohol.
• Early-morning waking: waking 1 to 2 hours too early and being unable to return to sleep. A classic feature of depression.
• Non-restorative sleep: sleeping enough hours but waking unrefreshed.

Most adults need 7 to 9 hours of sleep. Some people naturally need less and feel fine; insomnia is defined by daytime effects, not just hours.

Common causes of insomnia

Lifestyle and habits

• Caffeine from coffee, tea, energy drinks and cola. It stays in the body for 5 to 6 hours or more.
• Alcohol, which helps you fall asleep but causes waking in the second half of the night.
• Nicotine, a stimulant.
• Screens, work and bright light late in the evening.
• Irregular schedules, shift work, jet lag and long daytime naps.
• Heavy meals or exercise close to bedtime.
• A noisy, bright, hot or uncomfortable bedroom.

Stress and mental health

• Stress about work, money, relationships or health is the most common trigger of short-term insomnia.
• Anxiety: racing thoughts and worry at bedtime.
• Depression: early-morning waking or, less often, sleeping too much.
• Post-traumatic stress: nightmares and hypervigilance.
• Bipolar disorder: a reduced need for sleep can signal a manic episode.

Medical conditions

• Pain: arthritis, back pain, headaches and nerve pain.
• Breathing problems: asthma at night, COPD, heart failure and sleep apnea, which causes frequent waking.
• Restless legs syndrome: an uncomfortable urge to move the legs in the evening and at night, often linked to low iron stores.
• Acid reflux when lying down.
• Needing to urinate at night, from prostate enlargement, an overactive bladder or diabetes.
• Overactive thyroid: insomnia, anxiety, a fast heartbeat, tremor, weight loss and feeling hot.
• Menopause: hot flashes and night sweats wake people repeatedly.
• Pregnancy, especially the third trimester.
• Neurological conditions such as Parkinson's disease and dementia.

Medicines and substances

Decongestants, steroids, some antidepressants, beta-blockers, thyroid hormone (if the dose is too high), stimulants for ADHD, diuretics taken late in the day, and withdrawal from sleeping pills, alcohol or cannabis can all cause insomnia.

Insomnia with tiredness, feeling cold and anemia

This combination suggests looking for a physical cause:

• Iron deficiency anemia causes tiredness, breathlessness, pale skin and feeling cold, and low iron is a common trigger of restless legs, which keeps people awake. Treating the iron deficiency often improves both energy and sleep.
• Underactive thyroid causes tiredness, feeling cold, weight gain and constipation. It more often causes sleepiness, but it can disturb sleep through aches, low mood or associated sleep apnea.
• Depression can cause poor sleep with exhaustion.

A doctor can check with simple blood tests: a blood count, ferritin (iron stores) and thyroid function.

When to see a doctor

See a doctor if poor sleep lasts more than a few weeks, affects your work, mood or safety, or comes with snoring, breathing pauses, leg discomfort, low mood or other symptoms. Keep a sleep diary for 2 weeks: bedtime, how long it took to fall asleep, wakings, wake time, naps, caffeine, alcohol and how you felt the next day.

The doctor will ask about your sleep pattern, mental health, medicines and medical conditions. Blood tests may check for anemia, iron, thyroid problems or blood sugar. A sleep study is arranged when sleep apnea, restless legs or other sleep disorders are suspected.

What helps insomnia

Tonight

• Get up at the same time every day, including weekends, even after a bad night.
• Go to bed only when sleepy.
• If you cannot sleep after about 20 minutes, get up and do something quiet in dim light until you feel sleepy.
• Keep the bedroom cool, dark and quiet.
• Avoid screens and work for an hour before bed.
• Write down worries and a to-do list earlier in the evening.

Over the next few weeks

• Cut caffeine after midday and limit alcohol.
• Get bright daylight soon after waking and exercise during the day.
• Avoid naps, or keep them under 30 minutes before 3 p.m.
• Use the bed only for sleep and sex.

Medicines

Over-the-counter sleep aids containing sedating antihistamines (such as diphenhydramine or doxylamine) cause next-day grogginess and confusion in older adults and are not recommended for regular use. Melatonin helps mainly with jet lag and body-clock problems. Prescription sleeping pills are only for short-term use alongside other approaches.

For long-term insomnia, cognitive behavioral therapy for insomnia (CBT-I) is the recommended first treatment. See insomnia disorder for details of treatment options.

Frequently asked questions

Why can't I sleep even though I'm tired?

Being tired is different from being sleepy. Stress hormones, worry, caffeine, alcohol, screen use and an irregular schedule can keep your brain alert even when your body is exhausted. Pain, anxiety, depression, hot flashes and restless legs are common medical reasons.

Why do I keep waking up at 3 a.m.?

Waking in the early hours is common with stress, alcohol (as it wears off), needing to urinate, sleep apnea, hot flashes, pain and depression. Light sleep in the second half of the night makes waking easier. Avoid checking the clock and get up if you are awake longer than about 20 minutes.

How many hours of sleep is insomnia?

Insomnia is not defined by a number of hours. It means difficulty getting or staying asleep, at least 3 nights a week, with daytime effects such as tiredness, irritability or poor concentration. Lasting 3 months or more makes it chronic insomnia.

Can anemia cause insomnia?

Indirectly, yes. Iron deficiency is a common cause of restless legs syndrome, which makes it hard to fall and stay asleep. Anemia also causes fatigue and feeling cold, which can disturb sleep. A blood test for iron and ferritin is worth asking about if you have these symptoms.

Is it bad to take sleeping pills every night?

Regular nightly use of sleeping pills is generally discouraged. Over-the-counter antihistamine sleep aids lose effect and cause next-day grogginess, and prescription pills carry risks of dependence, falls and memory problems. CBT-I works better in the long term.