Health A-Z

Medical Content Created by the Faculty of the
Harvard Medical School

Insomnia

What Is It?

Insomnia is difficulty getting enough sleep or trouble sleeping without interruption. You may have difficulty falling asleep, may wake up too early, or may wake up periodically during the night. Insomnia of any kind can keep you from feeling rested and refreshed during the day. Almost all of us have episodes of insomnia at some time, but insomnia is not a short-term problem for everyone. Insomnia is classified as chronic when it happens almost every night for at least one month. Insomnia can be related to a medical or psychiatric illness, can be caused by mental stress or excitement, or can be caused by your daytime and bedtime habits.

Your habits and surroundings are the usual causes of short-term insomnia problems. Factors that contribute to insomnia can include:

• Stress or anxiety

• A change in sleeping environment (being a guest at a hotel or a relative's home)

• An uncomfortable sleeping environment (too hot, too cold, too bright, too noisy)

• An uncomfortable mattress

• Pajamas that are too tight

• Having a bed partner who snores or has disruptive sleep patterns

• Watching television, reading a book or problem-solving in your bed, so your brain associates lying down in bed without activities other than sleeping

• Eating a heavy meal before bedtime

• Taking a prescription medication that has insomnia as a side effect

• Drinking alcoholic beverages before bedtime

• Having a high intake of beverages containing caffeine (coffee, tea, cola) during the day

• Cigarette smoking

• Exercising immediately before bedtime

• Not exercising enough during the day, so you have energy to spare

• Taking a hot bath or shower before bed

• Traveling to a different time zone

• Traveling to a much higher altitude

• Shift work

Pregnant women are particularly vulnerable to insomnia. Women who are pregnant may have insomnia because of hormone changes, heartburn, leg cramps or a need to urinate more frequently. In addition, the unborn baby's increasing size often makes it harder for the mother to find a comfortable sleeping position.

Chronic insomnia may be caused by a medical or psychiatric problem. Some common causes of chronic insomnia include:

• Psychiatric illness, especially depression or post-traumatic stress disorder (PTSD)

• Chronic medical illnesses, especially kidney disease, heart failure or asthma

• Painful illnesses, especially arthritis, neuropathy, acid reflux or cancer

• Hormone imbalance, especially menopause or hyperthyroidism

• Taking a prescription medicine that has insomnia as a side effect

• Obstructive sleep apnea — Snorers or people who are overweight may have repeated episodes in which breathing stops for 10 seconds to 30 seconds during sleep, just when the person is relaxing into deep sleep. Sleep apnea is caused most often by relaxing the tongue and throat tissues, which can settle into a position that closes your airway. Your body reacts to sleep apnea by releasing adrenaline-like "alarm" hormones so you will awaken and resume breathing. These hormones keep you awake for periods of the night, and can cause high blood pressure that lasts through the day.

• Narcolepsy — In this condition, the patient's sleep is disturbed at night, but he or she falls asleep suddenly and involuntarily during the daytime

• Restless legs syndrome — This disorder causes uncomfortable sensations in the legs. Symptoms can include twitching of the legs, a habit of repetitive leg movements, and leg cramps.

An estimated 25% to 33% of people in the United States have some form of insomnia. Sleeping pills are usually not the best way to correct an insomnia problem, but they are among the most prescribed medicines in the United States. Women are affected more often than men, especially women older than age 60.