Why You Can't Sleep More Than a Few Hours (2024)

There are more than 100 different sleeping and waking disorders, and it is easy to confuse them. Sleep deprivation often occurs with sleeping disorders.

If you only sleep four to five hours per night (or less), you may have sleep deprivation. In addition, regular sleep interruptions from things like night terrors or "sleep starts" can also lead to sleep deprivation.

For example, if you need fewer than six hours of sleep every night and don't have sleep deprivation symptoms, you likely do not have insomnia. Instead, you may have a condition known as short sleep syndrome (SSS).

This article explains the difference between sleep deprivation and SSS.

Sleep Deprivation

Being unable to sleep can affect your health and well-being. Sleep disorders fall under the following categories:

• Insomnia: Difficulty falling asleep or staying asleep
• Hypersomnia: Excessive daytime sleepiness caused by narcolepsy, obstructive sleep apnea, and other medical conditions
• Circadian rhythm disorders: When your biological clock is out of sync, such as in jet lag, irregular sleep-wake syndrome, and shift work syndrome
• Parasomnias: Behaviors that interrupt your sleep, such as sleep terrors, sleepwalking, and REM sleep behavior disorder
  

All of these conditions can cause sleep deprivation. Often, they affect your ability to function normally as you go through your day. Symptoms of sleep deprivation include:

• Clumsiness
• Depression
• Difficulty learning
• Drowsiness
• Fatigue
• Forgetfulness
• Increased carbohydrate cravings
• Irritability
• Less interest in sex
• Loss of motivation
• Moodiness
• Trouble concentrating
• Weight gain

Short Sleep Syndrome

Unlike sleep deprivation, people with short sleep syndrome (SSS) regularly need fewer than six hours of sleep per night and can still function normally.

People with SSS perform well at work or school even though they have short periods of sleep. They don’t feel the need to take naps or catch up on sleep on weekends.

The cause of short sleep syndrome is not well understood. However, new research shows that genetics play a key role.

SSS and Gene Mutations

In one study, genome sequencing in people who naturally need less sleep showed a rare mutation of the ADRB1 gene. Those who inherited this gene had shortened sleep cycles and had high levels of β1-adrenergic receptors.

It is thought that gene changes like this interfere with a person's sleep patterns and drive for sleep. Usually, these kinds of sleep interferences cause symptoms of sleep deprivation, but in people with certain gene mutations, they don't.

While this provides one key piece to the puzzle, scientists believe it is only one part of why some people do well with a shortened sleep cycle.

Other Reasons for Short Sleep

There are many reasons why people have trouble staying asleep at night. Common reasons include the following:

• Stress
• Poor sleep environment caused by loud noises or light
• Too much caffeine
• Back pain
• Shifting hormones
• Drinking alcohol before sleep
• Eating before sleeping

Summary

Sleep deprivation can be caused by many different sleep disorders, including insomnia. It can cause symptoms that affect your ability to function throughout the day. For example, if you have sleep deprivation, you may have trouble concentrating, feel tired all of the time, or be crabby.

People with SSS, on the other hand, need less sleep. They do not experience negative symptoms as a result. In addition, research has found certain gene mutations in people with SSS.