How much sleep do I really need…?

“How much sleep do I reaaaaally need?”

“When is the latest possible time I can stay up to?”

“Just drink coffee.”

As students, these phrases might sound familiar for one reason or another. While sleep is necessary for ensuring healthy brain function, metabolism, and overall health, some believe they can function optimally with minimal sleep. This raises the perennial question: what is the least amount of sleep a person needs?

Generally speaking, the recommended sleep duration for teenagers like us is 8-10 hours per night (hr/n). Shocking, right?

However, some individuals can depend on less sleep without much harm, due to lucky genetics or environmental factors. Thus, this piece aims to explore the biological basis of short sleep, the impacts of sleep deprivation (ahem, ahem), and the question, “How much sleep do I actually need…?”.

Wanna be a Natural Short Sleeper?

Despite more conventional advice, there is a rare breed of individuals known as Natural Short Sleepers who can function well on 4hr/n to 6hr/n without experiencing extreme fatigue, mental decline, or other health issues. Unfortunately, there are very few such individuals, with some studies estimating the natural short sleeper group at a mere 1-3% of the population.

While human sleep is notoriously difficult to study, this trait has been successfully linked to mutations in certain genes, mainly DEC2 and ADRB1.

DEC2 was found in 2009, in a study conducted by Fu et. al. In the study’s findings, researchers found that individuals with mutant DEC2 averaged only 6.25hr/n, while those with wild-type DEC2 averaged 8.06hr/n. Furthermore, those with mutant DEC2 did not have sleep debt and were able to function normally.

In a twist of fate, the same team discovered 10 years later that a mutation in ADRB1 also enables low sleep. Through gene sequencing and linkage analysis, the scientists were able to find the exact chromosomal location of the mutation, which turned out to be a single-letter mutation in ADRB1. These findings were later further validated in vitro and in vivo studies. Notably, at the molecular level, mutant ADRB1 codes for a mutant beta-1 adrenergic receptor, which degrades more rapidly than the wild-type receptor protein, which could account for the difference in phenotype.

Moreover, through optogenetics (a way of modifying cells to be activated by light), the team found that neurons in the dorsal pons (a sleep-regulating section of the brainstem) that expressed wild-type ADRB1 were activated to rouse sleeping mice. This suggested that neurons expressing ADRB1 regulate the wakefulness response in mice.

When the same experiments were done on neurons in the dorsal pons expressing mutant ADRB1, they were found to be more easily activated. Furthermore, individuals with mutant ADRB1 had a greater proportion of wakefulness-promoting neurons than sleep-promoting neurons.

All these seem to suggest that mutant ADRB1 promotes natural short sleep, by rousing the brain and keeping it awake.

Due to these factors, and many more which have yet to be found, Natural Short Sleepers seem to benefit from this quirk in their sleep needs. They tend to have better sleep quality, are more positive, more energised and superior at multitasking. They can also tolerate more pain, are less affected by jet lag, and may even enjoy longer life expectancies.

What if I don’t just sleep?

Unfortunately, for most of us who aren’t blessed with this trait, sleeping for less than 6hr/n causes numerous physical and psychological detriments. These negative effects may result in a lower quality of life, should an individual be constantly sleep deprived.

Mentally, sleep deprivation has been linked to lower cognitive performance, slower reaction time, and difficulties in concentrating on tasks at hand (sound familiar?). Moreover, since most scientists agree that most learning and memory formation occurs at night, sleep deprivation also means lower absorption and retention of content learnt during the day. It also increases the chances of developing anxiety or depression and may make it harder to manage one’s emotions and stress.

Physically, it has been shown that sleep deprivation increases the risk of a whole host of diseases, such as high blood pressure, stroke, heart disease, type 2 diabetes and kidney disease. Furthermore, sleep deprivation also decreases the body’s immune response and can make one more susceptible to falling ill.

Just get used to it.

While some people may purport to be able to function on low sleep, they probably aren’t Natural Short Sleepers. Instead, they are more likely to be functioning temporarily under reduced sleep conditions and are consequently accumulating huge amounts of sleep debt. While one may recover from sleep debt, studies have shown four days are needed to recover from only an hour of sleep debt, with the recovery time growing as sleep debt accumulates. Unfortunately, we just can’t seem to adapt to less sleep.

Pushing it just by a bit…

If you’re still curious to know the limits of sleep, the Guinness World Records gives us a clue. While it no longer accepts sleep deprivation in its list of records, the longest documented duration without sleep was 18 days and 21 hours,achieved by Robert McDonald.

However, the record set in 1964 by Randy Gardner serves as the most well scientifically documented duration of sleep (11 days). At the time, using electroencephalograms and other tools, doctors found that he was medically healthy after the ordeal. However, Gardner himself reported that “the mental part is what went downhill [and] [t]he longer [he] stayed awake, the more irritable [he] got".

On the less extreme end, while certain online sources may claim that we can temporarily survive on 3hr/n to 4hr/n, or continuously survive on 4hr/n to 6hr/n, most experts say that most of us will, unfortunately, suffer from significant health deterioration. For instance, this author once felt like a walking zombie after two to three hours of sleep, after rushing out a weighted assignment.

Conclusion

So, how much sleep do we really need? Considering that our life as students requires large amounts of content absorption and retention, it would appear that the answer is, “as much as possible”. While it is possible to cram in those extra hours of revision or rush that project you were procrastinating on, the decrease in effectiveness for the days to come would likely offset those extra hours. So, while 8hr/n to 10hr/n is an unattainable luxury and 3hr/n to 4hr/n is probably not worth it, somewhere in between, like 6hr/n to 7hr/n, might just do the trick.

Hopefully.

References:

1. Blum, D. (2023, August 29). How Much Sleep Do You Need? Tips for Better Slumber at Every Age. The New York Times. https://www.nytimes.com/interactive/2023/07/07/well/live/sleep-better-age.html

2. Del Pozo, J., PhD. (2022a, October 4). Millions of people may have a genetic mutation to sleep 4–6 hours instead of 8. Psychology Today. https://www.psychologytoday.com/sg/blog/being-awake-better/202210/are-you-genetically-short-sleeper

3. Del Pozo, J., PhD. (2022b, October 4). Millions of people may have a genetic mutation to sleep 4–6 hours instead of 8. Psychology Today. https://www.psychologytoday.com/sg/blog/being-awake-better/202210/are-you-genetically-short-sleeper

4. Montgomery, A. (2024, January 28). Lessons from sleeplessness: The 60th anniversary of Randy Gardner’s world record. NPR. https://www.npr.org/2024/01/28/1227217274/sleep-deprivation-record

5. Short Sleeper Syndrome (SSS). (2024, May 1). Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/short-sleeper-syndrome-sss

6. Summer, J. V., & Summer, J. V. (2023, November 14). Is 5 hours of sleep enough? Sleep Foundation. https://www.sleepfoundation.org/sleep-faqs/is-5-hours-of-sleep-enough

7. Suni, E., & Suni, E. (2023, June 2). Short sleepers. Sleep Foundation. https://www.sleepfoundation.org/how-sleep-works/short-sleeper-syndrome

8. University of California San Francisco. (2019, August 27). After 10-Year Search, Scientists Find Second ‘Short Sleep’ Gene | UC San Francisco. After 10-Year Search, Scientists Find Second ‘Short Sleep’ Gene | UC San Francisco. https://www.ucsf.edu/news/2019/08/415261/after-10-year-search-scientists-find-second-short-sleep-gene