Key Points
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A sleep disorder is any condition that disrupts a healthy sleep cycle.
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Sleep disorders include insomnia, breathing disorders, parasomnias, circadian rhythm disorders, movement disorders, and hypersomnia.
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Not every sleep disorder is curable, but most are manageable.
Sleep disorders are among the most common types of health problems that Americans experience. That's why Snooze has a whole section devoted to them. However, what is a sleep disorder, and how do you know if you have one?
There are many different kinds of sleep disorders, and they have diverse symptoms. The one element all sleep disorders have in common is that they're different from normal, healthy sleep. So to understand what a sleep disorder is, first, you need to understand what healthy sleep is.
The Nature of Healthy Sleep
Sleep habits develop with age, and Snooze has discussed how babies' sleep develops elsewhere. Infant sleep patterns are quite chaotic, which is why new parents are so sleep-deprived. However, this article will focus on sleep disorders among adults because, by adulthood, your sleep should follow a specific pattern.
During a typical night, this pattern involves going through four stages of sleep in cycles of roughly one to two hours each. Each of the stages has its unique characteristics, but in brief, they are:
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Stage One: Light sleep
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Stage Two: Deeper sleep
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Stage Three: Deepest sleep
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Stage Four: REM sleep (lighter sleep with intensive dreaming)
It's not a problem if you wake up between cycles, so long as you fall asleep again quickly. The key trait of healthy sleep is that you go through the stages sequentially and string them together enough to last seven to nine hours each night.
"Sleep disorder" is a general term for how this ideal pattern goes wrong. It goes wrong a lot.
New Jersey doctors Sarah Holder and Navjot Narula, who are also directors of family medicine residency programs, explain in their 2022 article for American Family Physician, "Sleep disorders are common in the United States, with the Institute of Medicine estimating that 50 million to 70 million adults report chronically disturbed sleep. Current recommendations for adult sleep duration range from seven to nine hours; however, nearly 40 percent of Americans sleep six hours or less per night."
Many disorders have different causes, but experts generally group them into six categories.
Insomnia
Insomnia literally means "un-sleep" in Latin, and it describes any disruption to the sleep pattern that results in too little sleep. Difficulty falling asleep is the most common manifestation, but it also might mean waking up too early or waking up after a few hours and staying awake for hours.
Insomnia is most often a side effect of a different problem. Many people get transient insomnia during times of stress or disruption, like after the death of a loved one, the loss of a job, an upcoming exam, etc. Usually, insomnia passes once the situation resolves, so it's not anything to worry about.
However, long-term conditions bring long-term insomnia. Common causes of long-term insomnia include anxiety disorders, depression, post-traumatic stress disorder, chronic pain, and habitual drug use (both legal and illegal). The best way to handle the insomnia in those cases is to identify and address the underlying cause.
A minority of insomnia cases have no co-occurring ailment to explain them. This is called primary insomnia, and it's something of a mystery to medicine. Lifestyle changes such as good sleep hygiene sometimes work, and prescription drugs and over-the-counter supplements like melatonin can also help so long as you don't overdo them.
Breathing Disorders
How do you tell when someone is asleep vs. just resting? The easiest way to know is the breathing — that slow, deep, steady kind of breathing that they never do when they're awake. Breathing slows over the first three sleep stages — getting slowest in stage three — then becomes more agitated during REM sleep.
However, the fact that you aren't conscious of your breathing during sleep means that abnormalities can sneak in that you aren't even aware of. These abnormalities can still bring trouble to your life, so look out for the symptoms.
Snoring
Snoring is so common that most people don't think of it as a disorder, and indeed, it doesn't disturb the sleep of the snorer — it just disturbs the sleep of anyone within earshot. The cause of snoring is the relaxation of the throat muscles during sleep, making them vibrate as you breathe. Nasal congestion, allergies, obesity, and the use of alcohol and other sedatives all aggravate snoring.
Snoring isn't a problem if you sleep alone, but if your partner has sleepless nights due to your snoring, there are ways to reduce it. Oral appliances are the most common treatment, so ask your dentist or ear, nose, and throat doctor about what's appropriate for you. Snoring is also a possible sign of sleep apnea, which is a much more serious condition.
Sleep Apnea
When you have sleep apnea, your breathing stops briefly as you sleep. After a few seconds, your body's internal alarms go off and you start again, often with a snort or a gasp. This often doesn't wake you up, but it plays havoc with your sleep cycle because those frequent internal alarms prevent you from sleeping deeply.
Therefore, the most common symptom of sleep apnea is that you sleep a normal length of time, but you still feel tired and out of it during the day. This poor quality of sleep is bad for your health in many ways, causing or aggravating depression, heart disease, diabetes, and car accidents.
If you suspect you have sleep apnea, see a sleep specialist to test you and deliver a diagnosis. Such tests determine not only the existence of sleep apnea but its cause: Usually, it's an obstruction in the throat, but sometimes it's a brain malfunction. The doctor will recommend a proper course of treatment for either.
Sleep-Related Hypoventilation
Sleep-related hypoventilation is similar to sleep apnea in that you don't get enough air during sleep, leading to similar problems. With hypoventilation, the problem isn't that breathing stops altogether; it's too shallow and slow to provide enough oxygen.
Hypoventilation is usually a side effect of another condition, especially lung diseases or sedative drugs. If you can't resolve the underlying issue, breathing machines ensure you get enough oxygen during sleep.
Parasomnias
Parasomnias are the most varied and exotic group of sleep disorders. It's an umbrella term for all sorts of abnormal behavior and experiences during sleep. There are many of them, but for simplicity's sake, experts group them according to sleep stage.
Non-REM Parasomnias
During the non-REM sleep stages, some people engage in activities of which they have no memory. Since they usually aren't dreaming during these stages, the activities are often things that they do when they're awake — talking, eating, doing chores, etc. As their brains aren't fully functioning, they'll often do these things in weird ways, which is a safety hazard if they're trying to, say, drive or move a heavy object.
Another type of non-REM parasomnia is "night terrors," in which the sleeper screams, thrashes, or otherwise shows distress. They aren't having a nightmare, though — if you wake them, they don't remember anything.
Non-REM parasomnias are most common in children; the usual cure is simply growing up. If they persist into adulthood and lead to dangerous situations, consult a sleep specialist about how best to treat the problem.
REM Parasomnias
REM is the intensive dreaming stage of sleep, so it's unsurprising that some weird things happen. The most common problem during REM sleep is bad dreams, or nightmares. They happen to everyone sometimes, but it's worth seeing a doctor if you have persistent nightmares — it's sometimes a sign of an underlying problem like post-traumatic stress disorder.
More alarmingly, there are some people who act out their dreams, including bad ones. This condition, called REM sleep behavior disorder, is more dangerous than sleepwalking because of its potential for not just blundering but violence. Its causes are unclear, but it usually shows up in people with neurodegenerative disorders like Parkinson's disease.
A less dangerous but still unnerving REM parasomnia is sleep paralysis. Sleep paralysis is how your body normally fends off REM behavior disorder — while you're dreaming, your body is disconnected from the motor functions of your brain so that you don't move.
However, sometimes people wake up enough to realize they're paralyzed but still asleep enough to be seeing things. They often feel that some entity is in the room with them, sometimes sitting or lying on them so they can't move. It's frightening but basically harmless, and if it happens frequently, you come to recognize it, so you know it's not real.
Circadian Rhythm Disorders
Your circadian rhythm is the scientific name for your body's inner clock. Most people's inner sleep-wake cycle follows the sun: You wake up around the time it gets light and go to sleep after dark. Circadian rhythm disorders are variations of this pattern, and they fall into several categories:
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Delayed sleep phase: The rock-star cycle, falling asleep in the wee hours and waking up at midday or even afternoon
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Advanced sleep phase: Falling asleep in the early evening and awakening before dawn
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Jet lag: Difficulty adjusting to a new time zone
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Shift-work disorder: Difficulty adjusting to night shifts or changing shifts
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Irregular: Sleeping and waking at random times
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Non-24-hour: The circadian rhythm is longer than 24 hours, usually by an hour or two
The causes of jet lag and shift-work disorder are obvious: The disruption to the inner clock comes from the outside. Irregular and non-24-hour sleep cycles usually stem from other disorders, but advanced or delayed sleep phases seem largely innate. You've no doubt noticed that "larks" and "owls" start to sort themselves out in childhood, and their tendencies often run in families.
Some people are able to arrange their lives around their natural sleep cycle, but it's often difficult to be out of sync with society. A sleep specialist can help you retrain your sleep cycle through light therapy, medications, and lifestyle changes.
Movement Disorders
A movement disorder is any condition that causes abnormal movement — spasms, twitches, tremors, tics, and so on. Any of them can make sleeping harder, but the one most often to blame for sleep problems is restless legs syndrome (RLS).
RLS brings unpleasant sensations to the legs — crawling, tingling, creeping — that create a strong urge to move the legs around for relief. It's usually worse at night, so it has serious, sleep-disrupting powers.
The cause of RLS is uncertain. Iron deficiency is sometimes the culprit, so taking iron supplements brings relief, but not always. Different medications work with different patients, so you and your doctor might need to experiment to find out what works for you.
Hypersomnia
While the typical adult needs seven to nine hours of sleep a night, those with hypersomnia need more than that. If sleeping less than 10 hours at night leaves you dozing off during the day, this is you.
Like insomnia, hypersomnia can be either a side effect of another disorder or an issue unto itself. Depression, head trauma, and various nervous system diseases can bring hypersomnia. It's also sometimes a side effect of drugs and medications, especially sedatives.
Primary hypersomnia usually takes the form of narcolepsy. Narcoleptics fall asleep abruptly at random times, even when they aren't trying. They also drop straight into REM sleep without going through the other stages, and they often experience sleep paralysis and related hallucinations.
Narcolepsy is usually the result of a gene mutation, and there's no cure. Narcoleptics typically manage their condition with prescription drugs.
Don't Sleep on Your Sleep Disorder
Given the diverse nature of sleep disorders, your outlook varies a lot depending on what kind you have: Some are transient, some are curable, and some you just have to manage. Not all sleep disorders have to ruin your life — sometimes, you just work around them. However, don't hesitate to see a specialist if you have a sleep disorder that harms your health and happiness. Better sleep improves your life both day and night.
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