Sleep Disorders

Ryan Fiorenzi, BS, Certified Sleep Science Coach - Updated on March 22nd, 2023

According to the Centers for Disease Control and Prevention, more than 50 million Americans suffer from different sleep disorders, and a further 20 to 30 million suffer from intermittent sleep problems. 11% don't feel well-rested every night, and 70% of adults report poor sleep at least one night per month.

There are over 80 different sleep disorders, and the American Academy of Sleep Medicine classifies sleep disorders into the following categories:

  1. Insomnias: difficulty falling asleep and staying asleep
  2. Hypersomnias: causing a person to be extremely sleepy or falling asleep during the day
  3. Sleep-related breathing disorders: abnormal breathing that affects the quality of sleep
  4. Circadian rhythm disorders: sufferers don't fall asleep and wake up at normal times, such as shift work sleep disorder
  5. Parasomnias: events and experiences that occur while falling asleep, sleeping, or waking up like sleepwalking and night terrors
  6. Sleep movement disorders: movement before or during sleep that prevents restful sleep like bruxism or teeth grinding


Insomnia is defined as having trouble falling asleep or staying asleep. Insomniacs report some or all of the following:

  • Taking a long time to fall asleep.
  • Waking up during the night and not able to fall back asleep.
  • Waking up earlier than desired.
  • Feeling tired throughout the day.

The most common form of insomnia is when it's due to another medical condition, which is referred to as secondary insomnia. Primary insomnia isn't due to any medical, psychiatric, or environmental cause.

For more information on insomnia, check out our guide to insomnia.

Sleep Apnea

Obstructive sleep apnea is another common sleep disorder where the upper airways become blocked, resulting in the sleeper not breathing for periods of time. These events are called apneas.

Some of the common symptoms of sleep apnea are:

  • Excessive daytime sleepiness (hypersomnia).
  • Loud snoring.
  • Waking up during the night or in the morning with a dry mouth (a sign of excessive snoring).
  • Stopping breathing for periods during the night.
  • A headache in the morning.

If you'd like to learn more, check out our guide to sleep apnea.

Restless Legs Syndrome (RLS)

Restless legs syndrome (RLS) is an uncomfortable condition that causes people to move their legs to get rid of the uncomfortable sensation. This usually occurs at night, and often while sleeping, which prevents the sufferer from getting restful sleep.

There are two main types of RLS, the first of which is primary RLS, which has no known cause. The other is secondary RLS, which is associated with chronic kidney failure, iron deficiency, spinal cord damage, or peripheral neuropathy (damage to the nerves in your hands and feet, often due to diabetes).

For information, check out our guide to RLS.


Narcolepsy is a rare condition that occurs in two different forms: one with cataplexy, and the other without. Cataplexy is a sudden loss of muscle control when the person can fall or slur their words and is often caused by an emotion such as laughter or some kind of excitement. During cataplexy, the person is awake.

Narcolepsy without cataplexy is often less severe, and it's a sleep disorder that can cause the sudden onset of sleep, sleep paralysis, hallucinations, and excessive sleepiness. It affects around 1 in 2,000 people. People with narcolepsy can be very tired during the day and have vivid hallucinations and sleep paralysis while falling asleep and waking up. They also have disturbed sleep at night because the brain doesn't follow the normal flow through the different phases of sleep—people with narcolepsy can go directly from waking to REM (rapid eye movement) sleep, bypassing light sleep and deep sleep.

For more information, check out our guide on narcolepsy.


Sleepwalking is also known as somnambulism, and is a parasomnia (an unwanted behavior while asleep). Sleepwalkers walk or do other activities while asleep, yet part of their brain is awake. Sleepwalkers can do many different activities while asleep, such as having sex, cooking, driving, taking a shower, and getting dressed.

For more information, check out our guide on sleepwalking.

Night Terrors

Night terrors or sleep terrors are a parasomnia, and are different from nightmares in that they involve someone screaming and/or flailing while asleep, and often occur with sleepwalking. Night terrors are more common in children than adults, and episodes can last for a few seconds to a few minutes.

For more information on night terrors, check out our guide to night terrors.

Teeth Grinding

Teeth grinding while asleep (also known as nocturnal bruxism) is a common disorder. For people who do it often over a long period, it can result in loose teeth, worn-away enamel, and teeth that are ground down. Serious cases can lead to major dental work such as crowns, root canals, bridges, and implants.

For more information, check out our guide on how to stop teeth grinding.

Shift Work Disorder

Shift work sleep disorder (SWSD) is a circadian rhythm disorder that's relatively common, and it's caused simply by working when you should be sleeping. There are many variations in work schedules, but any time that you need to be awake while it's dark, and sleep when it's light outside, your brain becomes confused. Darkness will cause the release of melatonin, the sleep hormone, and light tells your brain that it's time to be awake.

Non-24-Hour Sleep Wake Disorder

Also known as hypernychthemeral syndrome, and abbreviated as non-24, it's considered to be a circadian rhythm disorder that's common among blind people with no light perception. It's estimated that 50%-75% of all blind people have non-24, as light exposure is the main way that our circadian rhythm is set.

All animals and plants have an internal clock, also known as the circadian rhythm. The internal clock regulates hormone production and sleep. In people with non-24, their circadian rhythms aren't on a 24-hour cycle. If they're on a 25-hour cycle, then they would go to sleep one hour later every night. Eventually, the person will realign with the 24-hour cycle, but then they start to go to sleep one hour later every night again.

Sleep Talking

Also known as somniloquy, sleep talking occurs without the talker being aware of it. It's normally gibberish, doesn't last for long periods, and is more common in males and children.

Sleep talking seems to have a genetic component as it runs in families, although it can be brought on by stress, alcohol, fever, depression, and sleep deprivation. Sleep talking often occurs with other sleep disorders such as sleepwalking.

Usually no treatment is required for sleep talking. If it's disturbing to a partner, it's recommended that the sleep talker take steps to reduce their stress and increase the chances of sleeping well by following some of the basic sleep hygiene rules, such as:

  • Going to bed and waking up at the same time every night.
  • Avoiding alcohol and large quantities of food before bed.
  • Reducing stress.
  • Creating a bedroom and nightly ritual that's sleep-inducing.

Jet Lag

Jet lag is a temporary problem with the circadian rhythm, affecting those who travel across time zones. The more time zones that one crosses, the longer it can take to reset to the local time zone. It also tends to be more difficult when traveling east. Frequent flyers tend to have more jet lag issues, as by the time they acclimatize to their new destination, it's often time to return home or to a new destination, where they stay for a few days, and then fly off again. Their circadian rhythms are constantly being disturbed. Another risk factor for jet lag is being elderly.

Jet lag can cause symptoms such as sleepiness, irritability, constipation, difficulties focusing, and difficulty falling asleep (insomnia). To help reset the circadian rhythm, one option is to supplement melatonin (the sleep hormone), which can help you to get to sleep. It's also advisable to pay attention to your exposure to light, as when your brain is exposed to light, it's receiving a signal that it needs to be awake. If you are traveling east and would benefit from sleeping "early" even though you aren't tired, it's recommended not to expose your brain to light (especially blue light radiated by tablets, TVs, and cell phones) for a few hours before bed.

Another option is before traveling, to start acclimating to your new schedule by going to bed 15-30 minutes earlier or later every night for a few days leading up to your trip, which will make the acclimation less extreme.

Another issue that can make jet lag worse is dehydration caused by very dry air in airplanes. Drink water before, during, and after your flight to prevent dehydration, and avoid alcohol and caffeine, which can affect sleep and increase the chances of dehydration.