If you’re regularly getting just four to five hours of sleep per night (or even less), it could be due to factors like stress, too much caffeine, or an uncomfortable sleep setting.
If this pattern persists, it may point to a sleep disorder such as insomnia, narcolepsy, or sleep apnea.
Over time, this can result in symptoms of sleep deprivation, including sleepiness, forgetfulness, and irritability.
If you’re consistently getting less than five hours of sleep without showing signs of sleep deprivation, it could be due to a condition called Short Sleep Syndrome (SSS), which is caused by a rare genetic mutation.
Sleep Deprivation
Sleep deprivation, or insufficient sleep, happens when you don’t get enough quality rest to support your health, alertness, or performance.
The National Sleep Foundation advises 7-8 hours of sleep for adults, 8-10 hours for teenagers, and 9-11 hours for children of school age.
Sleep deprivation can be short-term, lasting a night or two, and usually resolves after a few nights of rest.
But when it becomes chronic, it can severely impact your ability to function, leading to symptoms like:
- Clumsiness
- Depression
- Difficulty learning
- Drowsiness
- Fatigue
- Forgetfulness
- Craving carbohydrates
- Irritability
- Reduced interest in sex
- Lack of motivation
- Mood swings
- Trouble concentrating
- Weight gain
Common causes of sleep deprivation include:
- Intrinsic sleep disorders: Conditions like insomnia, narcolepsy, sleep apnea, or restless leg syndrome.
- Extrinsic sleep disorders: Factors like food allergies, alcohol-related insomnia, or poor sleep habits.
- Circadian rhythm disorders: Issues such as jet lag or shift work syndrome.
- Parasomnias: Disorders like sleepwalking or REM sleep behavior disorder.
Is Sleeping 4-5 Hours a Night OK?
Not everyone who sleeps less than the recommended amount has a sleep disorder or experiences sleep deprivation symptoms.
However, a 2022 study in PLoS One found that adults over 50 who slept less than five hours per night had a 30% higher risk of chronic diseases compared to those who slept seven hours.
This risk rose with age, reaching 32% at age 60 and 40% at age 70. These conditions include:
- Diabetes
- Cancer
- Coronary artery disease
- Stroke
- Heart failure
- COPD (chronic obstructive pulmonary disease)
- Chronic kidney disease
- Liver disease
- Depression
- Dementia
- Mental disorders
- Parkinson’s disease
- Arthritis
Short Sleep Syndrome (SSS)
Unlike sleep deprivation, people with Short Sleep Syndrome (SSS) need less than six hours of sleep per night and still function well without experiencing sleep deprivation symptoms.
Those with SSS perform well at work or school and don’t feel the need to “catch up” on sleep over the weekends.
While the exact cause of SSS is not fully understood, genetics is thought to play a significant role.
A 2019 study in Neuron found that people with SSS often carry a rare mutation in the ADRB1 gene, which is associated with shorter sleep cycles and higher levels of β1-adrenergic receptors.
These receptors help manage the body’s functions during the sleep-wake cycle. In individuals with the ADRB1 mutation, this cycle is “reprogrammed” to complete necessary biological and hormonal processes within a shorter time frame.
Further research is required to fully understand this phenomenon.
Other Causes of Short Sleep
Several factors can make it hard to get enough rest, often due to habits that disrupt sleep. Common causes include:
- Stress and anxiety
- Excessive caffeine or alcohol before bed
- Intense exercise close to bedtime
- Late-night eating
- Uncomfortable bedroom temperature
- Noisy or bright environments
- Irregular sleep schedules
- Exposure to electronics or LED light before bed
