Sleep is essential for the optimum functioning of many physiological processes inside the human body. In reality, we spend approximately one-third of our lifetime asleep.1 However, there are also working adults suffering from inadequate sleep. A local survey reported that more than half of the recruited Malaysian working adults had less than 7 hours of sleep daily.2
Having insufficient sleep is unhealthy. Such modifiable behaviour is a potential risk factor for the development of non-communicable diseases. For instance, the risk of acquiring cardiovascular disease is likely to increase the following deviation from the recommended sleep duration. Even a single hour of chronic sleep deficit may result in a higher chance to develop mental health disorders like depression or anxiety.
Sleep-deprived individuals may also be more susceptible to acute infections. Insufficient sleep affects our immune system by causing a decreased production of protective infection-fighting antibodies. Thus, longer recovery time may be needed after a simple viral infection. During the current COVID-19 pandemic, certain COVID-19 patients may get insomnia following an acute SARS-CoV-2 infection as a manifestation of long COVID. This may further reduce their quality of life.
In general, working adults should aim to sleep for 7 to 9 hours per night.3 Shorter sleep duration (less than 7 hours) is related to a higher release of appetite’s regulatory hormone (ghrelin) which may lead to obesity. Compared to 7 hours of sleep duration, extreme sleep deprivation (less than 5 hours) may cause calcification on the coronary artery (blood vessel which supplies oxygen-rich blood to the heart muscle), which increases the risk of a heart attack.
On the other hand, longer sleep duration is not recommended among healthy working adults. In fact, longer sleep duration (more than 9 hours) may raise blood vessel stiffness leading to high blood pressure, especially among the Asian population. Besides that, sleep timing may be altered following a longer sleep duration. This may cause a dysfunctional circadian rhythm (akin to jet lag disorder in the temporary form), leading to increased risks of insomnia.
Sleep quality which measures how well we sleep is equally important. If we spend more than 30 minutes falling asleep, have waking-up episodes at least twice in a night, or spend more than 20 minutes falling back asleep after awakening, the sleep quality is considered subpar.4 Obstructive sleep apnoea which causes poor sleep quality may increase cardiometabolic risks in the long term.
In summary, neither too short nor too long sleep durations are desired as both conditions are associated with a myriad of adverse health outcomes. In line with the ongoing ‘National Sleep Comfort Month’, every working adult should adhere to the recommended sleep duration (7 to 9 hours per night) and aim to have good sleep quality by practising healthy sleep hygiene (be physically active, avoid consuming alcohol or caffeine before bedtime or dim the room light upon sleeping).
This write-up was prepared by Dr Yap Jun Fai (DrPH candidate), Professor Dr Moy Foong Ming and Dr Lim Yin Cheng from the Department of Social and Preventive Medicine, Faculty of Medicine, Universiti Malaya. This write-up is also published in the CodeBlue.
1. Institute of Medicine (US) Committee on Sleep Medicine and Research; Colten HR, Altevogt BM, editors. Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem. Washington (DC): National Academies Press (US); 2006. 2, Sleep Physiology. Available from: https://www.ncbi.nlm.nih.gov/books/NBK19956/
2. Chan CMH, Siau CS, Wong JE, Wee LH, Jamil NA, Hoe VCW. Prevalence of Insufficient Sleep and Its Associated Factors Among Working Adults in Malaysia. Nat Sci Sleep. 2021;13:1109-1116.
3. Hirshkowitz M, Whiton K, Albert SM, et al. National Sleep Foundation’s sleep time duration recommendations: methodology and results summary. Sleep Health. 2015;1(1):40-43.
4. What Is Sleep Quality? National Sleep Foundation. Available from https://www.thensf.org/what-is-sleep-quality/