Sleep Disorders: Insomnia, Sleep Apnea, and More

February 2020

William C. Shiel Jr., MD, FACP, FACR

What Are Sleep Disorders?

Sleep disorders are conditions that impair a person’s ability to get normal restorative sleep. The causes of these conditions are variable and range from habits people have developed before they go to sleep to a number of medical problems that disrupt the normal sleep cycle. If you notice you have a pattern of not feeling rested in the mornings after you wake up, you should probably see your doctor to determine if you have a sleep disorder. Sleep disorders can have a profound effect on a person’s overall health.

Why Is Sleep Important?

Lack of sleep can be life-threatening! For example, car accidents, personal problems, poor job performance, injuries, memory problems, and mood disorders have been linked to poor sleep. I addition, researchers have concluded sleep disorders likely contribute to heart disease, obesity, and diabetes.

Symptoms of Sleep Disorders

Symptoms of sleep disorders vary depending on the type of sleep disorder. The symptoms may range from mild to severe and usually include one or more of the following: hypersomnia (excessive daytime sleepiness), insomnia (decreased sleep efficiency with unrestful sleep with frequent waking up in the night), loud snoring and/or brief pauses in breathing (short periods of apnea), leg movements or an urge to move the legs at night, sleepwalking, or night terrors (nightmares).

The Sleep Cycle

A normal sleep cycle has two major categories termed REM and non-REM. REM stands for rapid eye movement. REM sleep is characterized by muscle relaxation, dreaming, episodic rapid eye movements, and low amplitude waves on an EEG (encephalograph). Non-REM sleep is divided into four stages from light sleep (stage 1) to stage IV (Delta or deep sleep). Non-REM sleep occupies about 75% of normal sleeping time while REM occupies the remaining 25% and usually occurs more toward morning. Sleep disorders disrupt these sleep cycles.

How Much Sleep Do I Need?

The sleeping time needs of individuals are variable, and sleep times vary between kids and adults.


Some adults can vary in their sleep requirements from about 5 to as many as 10 hours per night. However, several studies have suggested the majority of normal adults average about 7 to 8 hours per night.

Younger People

In general, the younger the person, the more sleep they need. For example, teenagers require about nine hours of sleep while infants require about 16 hours per night.

What Is Insomnia?

Insomnia is the inability to initiate or maintain sleep. Most people in their lifetime will have some difficulty falling asleep occasionally. However, if trouble falling asleep occurs either frequently or steadily, the individual may have insomnia. People with insomnia have difficulty falling asleep, sometimes for hours at a time, and they may wake up too early or they may wake up repeatedly through the night. Insomnia is considered the most common sleep disorder in the U.S. and studies suggest as many as 95% of Americans have reported an episode of insomnia at some time during their life.

Causes of Insomnia: Sleep Hygiene

Poor sleep hygiene refers to bad habits that interfere with an individual’s ability to fall asleep. For example, drinking coffee or other caffeinated drinks in the evening, smoking, eating heavy foods late in the evening, falling asleep with the lights on and/or leaving the television on, or using a cell phone, computer, or tablet right before bed are bad habits or poor sleep hygiene can lead to insomnia.