Reasons Why You Only Sleep a Few Hours a Night

If you're only sleeping four to five hours a night (or less), it could be due to stress, consuming too much caffeine, or a poor sleep environment. If this happens regularly, it could be a sign of a sleep disorder such as insomnia, narcolepsy, or sleep apnea. This can lead to symptoms of sleep deprivation, including drowsiness, forgetfulness, and moodiness.

If you regularly sleep less than five hours and don't have signs of sleep deprivation, it could be due to a condition known as short sleep syndrome (SSS) caused by a rare gene mutation.

Sleep Deprivation

Sleep deprivation, also known as sleep insufficiency, is when you don't get enough quality sleep to support your health, alertness, or performance.

The definition of sleep deprivation can vary to some degree by age and other factors. As a baseline, the National Sleep Foundation recommends seven to eight hours of sleep per night for adults, eight to 10 hours per night for teens, and nine to 11 hours per night for school-aged children.

The sleep deprivation may be acute, lasting one or two nights, and usually be relieved with a night or two of quality sleep. When the deprivation is chronic, meaning persistent or recurrent, it can limit your ability to function normally, causing:

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

Common causes of sleep deprivation include sleep disorders like:

• Intrinsic sleep disorders: Including primary insomnia, narcolepsy, obstructive sleep apnea, central sleep apnea, and restless leg syndrome
• Extrinsic sleep disorders: Including food allergy insomnia, alcohol-induced insomnia, and poor sleep hygiene
• Circadian rhythm disorders: Such as jet lag and shift work syndrome
• Parasomnias: including sleep terrors, sleepwalking, and REM sleep behavior disorder

Is It OK to Sleep 4 to 5 Hours a Night?

Not everyone who sleeps less than the recommended hours per night has a sleep disorder or will exhibit signs of sleep deprivation.

However, a 2022 study published in the journal PLoS One reported that adults 50 and over who slept less than five hours a night had a 30% higher risk of multiple chronic diseases compared to those who slept seven hours. By age 60, the risk increased to 32% and, by age 70, to 40%.

These include chronic diseases like:

• Diabetes
• Cancer
• Coronary artery disease (CAD)
• Stroke
• Congestive heart failure (CHF)
• Chronic obstructive pulmonary disease (COPD)
• Chronic kidney disease (CKD)
• Liver disease
• Depression
• Dementia
• Mental disorders
• Parkinson’s disease
• Arthritis

Short Sleep Syndrome

Unlike sleep deprivation, people with short sleep syndrome (SSS) need fewer than six hours of sleep per night and can still function normally without signs of sleep deprivation.

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 SSS is not well understood, but genetics is thought to play a major role.

According to a 2019 study published in the journal Neuron, people who meet the criteria of SSS tend to have a rare mutation of the ADRB1 gene. This mutation is associated with shortened sleep cycles and higher levels of β1-adrenergic receptors. These receptors regulate, among other things, body functions during the circadian (sleep-wake) cycle.

The circadian rhythm is largely synchronized to day and night. In people with the ADRB1 mutation, the cycle—and the biological and hormonal changes the body needs to undergo during sleep to function normally—is "reprogrammed" so that these functions are performed within a shorter period. More research is needed.

Other Reasons for Short Sleep

There are many other reasons why people have trouble staying asleep at night, including habits that contribute to sleeplessness. Common reasons include:

• Stress and anxiety
• Consuming too much caffeine or alcohol before bedtime
• Exercising too vigorously before bedtime
• Late-night snacks before bedtime
• Too hot or cold bedroom temperatures
• Loud or bright bedroom environments
• Irregular sleep schedules
• Electronics or exposure to LED light before bedtime

When to Contact a Healthcare Provider

Experiencing occasional insomnia may be aggravating but is usually not of serious concern to your health or well-being. However, it may be of concern if disrupted sleep is ongoing and affecting your ability to function.

See a healthcare provider if you experience:

• Insomnia for longer than four weeks
• Persistent daytime sleepiness, jitteriness, or "brain fog"
• Sudden gasping for breath that awakens you up at night
• Uncomfortable "crawling" sensations in your legs that interfere with sleep
• Heartburn that regularly awakens you at night

Your provider may refer you to a sleep specialist to undergo an overnight sleep study (also known as a polysomnogram) to pinpoint the causes of disrupted sleep.

How to Get More Sleep

Oftentimes, adjustments in your sleep hygiene can help overcome insomnia, a condition that chronically affects 17.8% of adults in the United States. Sleep hygiene refers to refers to healthy habits that can be adjusted to help you have a good night's sleep.

Recommended changes include the following:

• Keep a consistent sleep schedule.
• Engage in relaxing activities, like listening to soft music or taking a warm bath, before bedtime.
• Keep your bedroom dark with blackout curtains or by wearing a night mask.
• Maintain a cool temperature in your bedroom; use a fan or air conditioner in warm weather.
• Keep your bedroom quiet or use earplugs or a white noise machine to block noise.
• Don't use electronics, including video games, or play on your cell phone, before bedtime.
• Avoid food, caffeine, and alcohol three to four hours before sleep.
• Practice stress management techniques such as mindful meditation, breathing exercises, guided imagery, and progressive muscle relaxation (PMR) before bedtime.

If these interventions fail to overcome chronic sleep difficulties, speak with your healthcare provider.

Summary

Sleep deprivation can be caused by different sleep disorders, including primary insomnia, narcolepsy, sleep apnea, and jet lag. It can also be caused by poor sleep hygiene, including the consumption of caffeine or alcohol before bedtime. Whatever the cause, sleep deprivation can interfere with your ability to function normally and lead to long-term health concerns.

People with short sleep syndrome (SSS), on the other hand, need less sleep and do not experience negative symptoms as a result. SSS is believed to be associated with a specific gene mutation.