Author: Daira Trušinska
What is insomnia?
Sleep is one of the basic human needs required for good health and quality of life. Every now and then many of us experience restless nights when the events of the day or the anticipation of what’s to come
The World Health Organization (WHO) defines insomnia as chronic inability to obtain adequate sleep. The three main complaints are:
- difficulty falling asleep (sleep onset insomnia)
- interrupted sleep characterized by frequent awakenings (maintenance insomnia)
- early morning awakening
Another important criterion is that daytime fatigue must be present. Someone who has restless sleep at night but feels well during the day can’t be said to suffer from insomnia.Insomnia is considered chronic if it occurs at least three nights per week for three months or longer.
Insomnia is often blamed on unhealthy sleep habits, stress or specific substances. Research now shows that insomnia may be linked to depression, heart disease, and other physiological disorders. Two genome-wide association studies published on “Nature Genetics” provide insight into the biological basis of insomnia, revealing specific genes and showing links with heart disease and psychiatric disorders.
New promising studies
Both of the studies are genome-wide association studies (GWASs) that analyze DNA from thousands of people. These studies involve rapidly scanning markers across the sets of DNA of many people to find genetic variations linked with a particular disease. When new genetic associations are found, scientists can use the data to develop better approaches to diagnosis, treatment and prevention of the disease. The studies were carried out using the UK Biobank – a database of genetic, physical and health data collected on people in the UK from 2006 to 2010.
Researchers at Vrije Universiteit in Amsterdam led by geneticist Danielle Posthuma have carried out a GWAS that searches for links between particular symptoms and behaviors related to insomnia and shared sequences of DNA. The prevalence of insomnia in the people whose genomes were analyzed was approximately 30% which corresponds to the estimated prevalence in the general population. Having analyzed the genomes of more than a million people, the authors say it’s the largest GWAS to date. The researchers found 956 genes that foresee some risk of developing insomnia. Many of the same genes have been previously linked with depression, diabetes and cardiovascular disease.
The second study from researchers at Massachusetts General Hospital led by geneticist Richa Saxena identified 236 genes linked to insomnia after analyzing genomes of more than 450,000 people. Furthermore, the scientists analyzed data from almost 84,000 participants who had used motion detectors to register restless movements at night or sleepwalking. This enabled them to make connections between objective measures of sleep and their genetic findings. Once again there appeared to be a link between insomnia and genes involved with depression and coronary artery disease. 
How will this knowledge benefit human health?
Research in genetic components of diseases allows scientists to move a step closer to personalized medicine which means customizing medical treatment to the individual characteristics of each patient, as well as to provide patients with information about their individual risks of developing diseases and initiating early prevention.
“Identifying these genetic targets could allow researchers to more effectively tailor medicines and therapies,” geneticist Danielle Posthuma says.
In addition, knowledge about how diseases are linked to other comorbidities could help to develop new drugs that simultaneously target not only insomnia but also cardiovascular or psychiatric diseases. A good example of the significance of studies like this is cognitive behavioural therapy (CBT) which is based on the idea that by becoming aware of inaccurate or negative thinking challenging situations can be viewed and responded to in a more effective way. CBT targets insomnia and mood disorders, such as depression at the same time. The genetic overlap between insomnia and psychiatric disorders identified in these studies may explain this efficacy. Even though a lot of research is still needed, science is rapidly progressing towards the goal of using genetic information to develop therapies that are most suitable for each individual patient.
- Doghramji, K. (2006, May 15). The Epidemiology and Diagnosis of Insomnia. Retrieved from https://www.ajmc.com/journals/supplement/2006/2006-05-vol12-n8suppl/may06-2307ps214-s220
- Riba, F. J. (1993, January 01). Insomnia: Behavioural and cognitive interventions. Retrieved from https://apps.who.int/iris/handle/10665/58229
- Genome-Wide Association Studies Fact Sheet. (2015, August 27). Retrieved from https://www.genome.gov/20019523/genomewide-association-studies-fact-sheet/
- Bahcall, O. G. (2019). UK Biobank. Retrieved from https://www.nature.com/collections/bpthhnywqk
- Price, M. (2019, February 25). Insomnia tied to depression, cardiovascular disease. Retrieved from https://www.sciencemag.org/news/2019/02/insomnia-tied-depression-cardiovascular-disease
- Makin, S. (2019, March 12). A Genetic Basis for Insomnia Emerges from the Twilight. Retrieved from https://www.scientificamerican.com/article/a-genetic-basis-for-insomnia-emerges-from-the-twilight/
- Cover source – photo by Alexandra Gorn on Unsplash