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, sleep becomes 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 busy world that not only expects activity, but productivity. Despite its association with both an individual’s physical and mental wellbeing, it repeatedly fails to be adequately addressed by educational bodies, when the issue of early starts to 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 in discussions surrounding health and have people begun to adapt to require less sleep to function in society to keep up with the demands of productivity to survive?
The scientific study of sleep began with physiological studies that examined a person’s circadian rhythms during times of sleep and wakefulness. Le probleme physiologique du sommeil by French scientist Henri Pieron was the first published book to analyse sleep from these physiological perspectives in 1913. In the 1920s, Dr. Nathaniel Kleitman further studied these circadian rhythms to define sleep characteristics in different populations and the effect of sleep deprivation on the body. It was in 1953, that Dr. Kleitman’s research led to the discovery of Rapid Eye Movement (REM) sleep. By the late 1950s, Dr. William C. Dement continued on the research of his teacher Dr. Kleitman in the field of REM sleep to find that REM sleep was a stage within the sleep cycle. This discovery sparked the interest of scientists within the fields of electro-physiology, pharmacology, biochemistry and psychology to study the stages of the sleep cycle and the sensation of dreaming.
With these fields now interested in the relationship between sleep and health, sleep apnea, which is when a patient repeatedly stops and restarts breathing while asleep, was discovered in Europe in 1965 by scientists Gastant, Jung and Kuhlo. In 1970, the Stanford University Sleep Disorders Clinic was established to specifically diagnose and treat patients with sleep problems. Through examining respiratory and cardiac readings in their sleep tests, the clinic investigated the symptoms attributed to and avenues of treatment for Pickwickian syndrome, narcolepsy and insomnia; bringing sleep from the laboratory to a clinical discipline in medicine by 1972.
These published reports and academic journals were the basis for groups, such as the American Sleep Disorders Association, to advise the public on healthy sleeping habits based on the results generated from large samples of people examined. As technology advanced, with tests being able to run faster and cheaper in the laboratory, scientists began to look in depth at the genes that have an effect on the circadian rhythm and the genes that are involved in the sleep cycle.
A study entitled “Gene linked to needing less sleep identified”was published in the journal Cell Press in August 2019, in which scientists Ptáček, Fu et al. discovered that individuals with the Kindred 50025 allele are subjected to natural short sleep, which the authors refer to as a “lifelong tendency to sleep only between 4-6 hours per night”, describe feeling well-rested. They began by screening individuals with “unusual sleep patterns” in families and tested against family members who did not show tendencies for short sleep.
The group used SNP-based linkage analysis, a technique used to identify individual base differences between two alleles of the same gene, to identify the Kindred50025 allele in the ADRB1 gene, on chromosome 10. This alteration in one base leads to a difference in amino acid formation (alanine is instead valine) in the coding sequence of the gene. According to the Exome Aggregation Consortium database, this mutation occurs only 4.028 times per 100,000 individuals in the population.
Once the Kindred50025 allele had been identified, Ptáček, Fu et al. tested it to determine what functional differences were a result of the mutation. Using CRISPR/Cas9 technology, they were able to “knock-in” the altered gene into mice, with the mutant mice showing a decrease in the β1AR levels, having a subsequent decrease in the activation of the cyclic-AMP signalling cycle, as opposed to the control mice. The mutant mice were then subjected to the ANY-maze and electroencephalogram tests to judge their sleep/wake behaviours. The results of the tests told scientists that the mice with the Kindred50025 allele were more mobile during a 24-hour period with both light and dark phases. The mice also clocked in 55 mins less sleep than that of the control mice, in which the mutated allele was absent.
With the first work on natural short sleep being published in 2009, the genetic components of sleep are still in their infancy in terms of research and study, given that this most recent study used a small nuclear family, a sample much smaller than the historical studies in the 1950s and 1960s. However, with the identification of the Kindred50025 as a novel sleep gene, 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 into drug research on the sleep cycle and sleep/wake behaviour in individuals, but with such a small percentage of this allele being identified in the population, it is unlikely that most students will report the same sensation of well-restedness after only 5 hours of sleep. In the meantime, the takeaway from this study is that the Kindred50025 allele it is an allele to look out for in your 23andMe results.