Short sleep syndrome is a condition that allows 1% of the population to operate on less than six hours of sleep with no daytime difficulties.
People who are short sleepers also exhibit signs of hypomania, impulsivity, and a high reward drive.
Short sleep syndrome is not to be confused with a condition like insomnia, which causes people to get very little sleep but suffer daytime tiredness.
People with short sleep syndrome sleep 4-6 hours per night and still feel well-rested and alert the next day. Though this rare condition affects roughly one percent of the population, there are a number of well-known people who claim to regularly operate on very little sleep, including Barack Obama, Martha Stewart, and Jack Dorsey, the founder of Twitter.
Here's what you need to know about short sleep syndrome, including its symptoms, causes, and treatments.
Related: How Glow Recipe's popular Glow Sleeping Mask is made
Overview of short sleep syndrome
Sleep experts may refer to a person with short sleep syndrome as a "habitual short sleeper" (HSS) and "natural short sleeper (NSS)," says Paula G. Williams, PhD, associate professor in the department of psychology at University of Utah who has studied short sleepers.
Although approximately 30% of Americans report regular bouts of short sleep, many are not short sleepers from a clinical standpoint since they do not feel well-rested the next day.
The primary symptom of short sleep syndrome is consistently sleeping six hours or less and feeling fully functional the next day. However, from her research Williams has found other traits that tend to be consistent among most short sleepers.
"Those who do not report daytime dysfunction related to their short sleep and are characterized by hypomania, impulsivity, and high reward drive would meet the criteria of a short sleeper," says Williams. "They tend to engage in stimulating activities that allow them to override sleepiness."
Williams says short sleep syndrome is much different than a condition like insomnia. For example, people with insomnia would be characterized by higher anxiety. "These individuals usually report fatigue, non-restoration, and dissatisfaction with their short sleep," she says.
How short sleep syndrome is diagnosed
Many people with short sleep syndrome may not seek a diagnosis from a doctor because they aren't experiencing adverse health effects, says Lynelle Schneeberg, PsyD, an assistant professor at Yale School of Medicine and American Academy of Sleep Medicine Fellow.
However, you may be suffering from lack of sleep and not even realize it. So, if you're getting 6 hours of sleep a night or less, it's important to get a diagnosis, Shneeberg says. "It would be ideal to rule out insomnia and other medical sleep disorders, such as sleep apnea, which can cause disrupted sleep."
When making a diagnosis, a doctor will look for common behaviors that people with short sleep syndrome tend to exhibit:
They usually have had this sleep pattern most of their lives, since childhood or young adulthood, and are a short sleeper regardless if it's a weekday, weekend, or during a vacation.
They don't use sleep aids to fall asleep — they just naturally fall asleep around the same time each night, sleep six hours or less, and wake up around the same time each day feeling alert.
Short sleepers instinctually tend to sleep set hours each night. Conversely, someone with a sleep disorder may report waking up several times in the night and not feeling rested the following day.
Schneeberg says anyone experiencing irregular sleep patterns could benefit from a "sleep checkup." In this case, they may be asked to track their sleep via an app, such as CBT-i Coach, a wrist-worn wearable device, or a handwritten sleep log which you can download from an organization like the American Academy of Sleep Medicine (AASP).
After tracking their sleep patterns for 14 days, the doctor may order an electroencephalogram (EEG), which would record the person's brain waves. At the same time, their heart functioning would be collected through electrocardiography (ECG). These would both help in making an assessment about someone's sleep health and whether or not they are a short sleeper or if their brain activity indicates a sleep disorder such as insomnia.
The causes of short sleep syndrome
Little is known about the cause of short sleep syndrome, but researchers have found convincing evidence that at least part of it is genetic.
One of the leading researchers in this field is Ying-Hui Fu, PhD, a professor of neurology at the University of California, San Francisco, and a member of the UCSF Weill Institute for Neurosciences who has been studying short sleepers for nearly 25 years. Which is no easy feat since they make up about 1% of the population.
Over the years, she has discovered a few of what she calls "short sleep" genes:
In 2009, Fu and her fellow researchers identified a genetic mutation, DEC2, known to affect circadian rhythms.
After doing DNA screenings on several hundred blood samples from 70 families of people who had participated in sleep studies, they found the mutation in two people, a mother and a daughter. Both exhibited common symptoms of short sleepers because they averaged approximately 6.25 hours of sleep per night, slept from about 11 p.m. to 5 a.m. each night, and felt functional the next day.
Fu and her colleagues then further tested DEC2 in animals. The scientists bred mice and fruit flies with the same mutation and they slept less, and recovered faster, than mice and fruit flies without the mutation.
Ten years later, in mid-2019, Fu and her team revealed findings from a second "short sleep" gene in a family that had three successive generations of people who exhibited symptoms of short sleep syndrome.
They discovered a single-letter mutation in the ADRB1 gene and then tested their findings with mice to confirm that the mutant form of ADRBI promotes natural short sleep.
Interestingly enough, the family with the mutation in their ADRB1 gene lacked the DEC2 gene from Fu's 2009 findings. Therefore, suggesting that short sleep syndrome is not limited to a specific gene, but is more complicated.
In October 2019, Fu and her colleagues reported finding a third "short sleep" gene when they identified a point mutation in the neuropeptide S receptor 1 (NPSR1).
They discovered it in a father and son — who average 5.5 and 4.3 hours of sleep per night — when doing whole exome sequencing in a family of short sleepers and the findings were published in Science Translational Medicine. Similar to the short sleepers with the DEC2 and ADRBI genes, the father and son, too, naturally slept less than six hours per night and did not experience adverse effects from their short sleep patterns.
The researchers then analyzed the mutation in mice and found they were more active and slept less — and did not have cognitive impairment as a result. In addition, the study's findings suggest that NPSR1 prevents memory problems that usually happen due to sleep deprivation — and it's the first gene found to do so.
Treatment for short sleep syndrome
According to the National Sleep Foundation, since short sleepers are functional in the daytime and not impaired by shortened amounts of sleep, treatment is not typical or required.
Schneeberg agrees. "It's not treatable if the person truly is a short sleeper," she says. "So they should just continue being a short sleeper — and consider themselves lucky since most of us would prefer more time in our day for doing what we enjoy."
However, Jerry Siegel, PhD, professor of psychiatry and biobehavioral sciences at UCLA Center for Sleep Research, says "a distinction must be made between people who spontaneously sleep less than the average person and people who are deprived of sleep for one reason or another."
If they can be described as having insomnia or another sleep disorder, as opposed to being a short sleeper, these criteria will go into any diagnosis or treatment.
Meanwhile, "the only recommended treatments for sleep are behavioral," he says, such as going to sleep and getting up at the same time every day and not ingesting stimulants, like caffeine, before bed.
According to the CDC, other good sleep hygiene practices include not using electronic devices before bedtime and avoiding large meals for 2-3 hours before bed, as well as getting some exercise during the day.
Long-term health effects of short sleep syndrome
Just because short sleepers don't suffer these side effects doesn't necessarily mean that getting only 4-6 hours of sleep each night is harmless. Researchers just haven't found any long-term health effects, yet. Though Fu told Business Insider her lab is looking into it.
Williams, too, says the jury is still out on whether some people who get less than six hours of sleep really have no adverse health outcomes.
"So far, I haven't been convinced that anyone can really 'get away' with short sleep without repercussions, even if they don't perceive them," says Williams. "We simply don't know whether those types of people will avoid the consequences of short sleep, including cardiovascular disease, inflammation, cognitive deficits, weight gain, mood disturbance, and all-cause mortality."
To Williams' point, a 2010 report found that short sleepers are at risk for heart disease. Similarly, Williams and her colleagues have found preliminary evidence to suggest that the lack of perceived daytime dysfunction among some habitual short sleepers does not confer protection against risk of cardiovascular disease.
In other words, despite reporting that they didn't need more sleep, the short sleepers exhibited a higher risk of cardiovascular disease, she says.
Overall, Willliams says even though short sleepers "feel fine" on less sleep and don't appear to have metabolic problems, she thinks there needs to be additional research on their objective functioning, both mentally and physically.
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