Counting sheep vs burning the midnight oil: How much sleep should we get?

Image Credit: Claudio Scott

Despite the World Health Organisation’s recommendation for young adults to get between 7-9 hours of sleep each night, there have been reports of people functioning better on average on as few as 5 hours a night. Dylan O'Neill investigates this phenomenon.

Sleep. When you’re a child you never want to fall asleep,too afraid of missing out on the world around you. As you grow older, sleepbecomes more of a valued commodity, often sacrificed for an extra hour of work,training for a sporting event or dedicated to a hobby. For a lot of students,by the time they reach university, sleep is a fleeting respite from the busyworld that not only expects activity, but productivity. Despite its associationwith both an individual’s physical and mental wellbeing, it repeatedly fails tobe adequately addressed by educational bodies, when the issue of early startsto attend exams and late nights to meet deadlines is brought up by students,and merely joked as being part of the “student experience.”

Why has our relationship with sleep been overlooked indiscussions surrounding health and have people begun to adapt to require lesssleep to function in society to keep up with the demands of productivity tosurvive?

The scientific study of sleep began with physiologicalstudies that examined a person’s circadian rhythms during times of sleep andwakefulness. Le probleme physiologique dusommeil by French scientist Henri Pieron was the first published book toanalyse sleep from these physiological perspectives in 1913. In the 1920s, Dr.Nathaniel Kleitman further studied these circadian rhythms to define sleepcharacteristics in different populations and the effect of sleep deprivation onthe body. It was in 1953, that Dr. Kleitman’s research led to the discovery ofRapid Eye Movement (REM) sleep. By the late 1950s, Dr. William C. Dementcontinued on the research of his teacher Dr. Kleitman in the field of REM sleepto find that REM sleep was a stage within the sleep cycle. This discoverysparked the interest of scientists within the fields of electro-physiology,pharmacology, biochemistry and psychology to study the stages of the sleepcycle and the sensation of dreaming.

With these fields now interested in the relationship betweensleep and health, sleep apnea, which is when a patient repeatedly stops andrestarts breathing while asleep, was discovered in Europe in 1965 by scientistsGastant, Jung and Kuhlo. In 1970, the Stanford University Sleep DisordersClinic was established to specifically diagnose and treat patients with sleepproblems. Through examining respiratory and cardiac readings in their sleeptests, the clinic investigated the symptoms attributed to and avenues oftreatment for Pickwickian syndrome, narcolepsy and insomnia; bringing sleepfrom the laboratory to a clinical discipline in medicine by 1972.

These published reports and academic journals were the basisfor groups, such as the American Sleep Disorders Association, to advise thepublic on healthy sleeping habits based on the results generated from largesamples of people examined. As technology advanced, with tests being able torun faster and cheaper in the laboratory, scientists began to look in depth atthe genes that have an effect on the circadian rhythm and the genes that areinvolved in the sleep cycle.

A study entitled “Gene linked to needing less sleepidentified”was published in thejournal Cell Press in August 2019, inwhich scientists Ptá?ek, Fu et al. discovered that individuals with the Kindred50025 allele are subjected to natural short sleep, which the authors refer toas a “lifelong tendency to sleep only between 4-6 hours per night”, describefeeling well-rested. They began by screening individuals with “unusual sleeppatterns” in families and tested against family members who did not showtendencies for short sleep.

The group used SNP-based linkage analysis, a technique usedto identify individual base differences between two alleles of the same gene,to identify the Kindred50025 allele in the ADRB1gene, on chromosome 10. This alteration in one base leads to a differencein amino acid formation (alanine is instead valine) in the coding sequence ofthe gene. According to the Exome Aggregation Consortium database, this mutationoccurs only 4.028 times per 100,000 individuals in the population.

Once the Kindred50025 allele had been identified, Ptá?ek, Fuet al. tested it to determine what functional differences were a result of themutation. Using CRISPR/Cas9 technology, they were able to “knock-in” thealtered gene into mice, with the mutant mice showing a decrease in the ?1AR levels, having a subsequentdecrease in the activation of the cyclic-AMP signalling cycle, as opposed tothe control mice. The mutant mice were then subjected to the ANY-maze andelectroencephalogram tests to judge their sleep/wake behaviours. Theresults of the tests told scientists that the mice with the Kindred50025 allelewere more mobile during a 24-hour period with both light and dark phases. Themice also clocked in 55 mins less sleep than that of the control mice, in whichthe mutated allele was absent.

With the first work on natural short sleep being publishedin 2009, the genetic components of sleep are still in their infancy in terms ofresearch and study, given that this most recent study used a small nuclearfamily, a sample much smaller than the historical studies in the 1950s and1960s. However, with the identification of the Kindred50025 as a novel sleepgene, the report states that even when the allele is in a carrier individual -a person who has the allele, but it doesn’t have the same identifiable expression- their total sleep time is 7.5 hours, an hour shorter than the population.

This study will undoubtedly pave the way to research intodrug research on the sleep cycle and sleep/wake behaviour in individuals, butwith such a small percentage of this allele being identified in the population,it is unlikely that most students will report the same sensation ofwell-restedness after only 5 hours of sleep. In the meantime, the takeaway fromthis study is that the Kindred50025 allele it is an allele to look out for inyour 23andMe results.