Mind over Matter: Sleep Research, Impacts on Life

The concept of sleep has been a pertinent phenomenon of interest and is arguably one of the most crucial human activities. Its complexity and role in proliferating human life have intrigued scientists for decades. The onslaught of assignments and exams brought on by a heavy academic workload can cause many students to prioritize academics. The same can be said for increased workloads for workers around the world. Science has repeatedly shown, however, that the sacrifice of sleep not only hurts academic and work performance, but can set individuals up for worse cognitive function and performance in the days following a deficient sleep session.

In a study that observed 100 college students in an introductory chemistry class, students who slept 6.5 hours received grades that were 50% worse than those who slept 7.5 hours.[1] However, the study also revealed that regardless of the amount of sleep an individual received that night, their academic performance would diminish if they slept after a certain period of time. While this period of time is not the same for everyone, the average timestamp for students was 2 A.M. 

Many of our lives have been indelibly marked by the constant barrage of adequate sleep statements. However, the phrase, ‘Get a good night’s sleep, you’ve got a big day tomorrow,’  MIT professor Jeffrey Grossman says, is not entirely correct. When it comes to, for example, test-taking, “the sleep you get during the days when learning is happening” matters most, according to Grossman. 

Sleep can also play a major role in our mood, how we navigate our relationships, and even what foods we choose to eat. 

At the University of Pennsylvania, researchers found that participants who received 4.5 hours of sleep in one night out of the week felt greater mental exhaustion and stress, and decreased attention-sustaining abilities.[3] This can translate to broader complications that can affect our day-to-day lives, such as brain fog, inability to pay attention during conversations, and unnecessary stress. 

Such research is correlated to the prefrontal amygdala, which is ubiquitously known as the site of the “fight or flight” response. When an individual lacks adequate sleep, the brain is thrust into high alert, causing an individual to lose control over the slightest hint of a threat. Sleep experts believe that the overactivity in the prefrontal region of the brain is the cause for such a reaction, as the brain is no longer able to control the prefrontal area after a long night of sleep deprivation.[4] 

On top of the internal complications that arise when an individual lacks sleep, human interaction can also become harder to navigate. Studies have shown that sleep deprivation is correlated with lower empathy.[5] 

The foods we choose to eat are also reliant on the amount of sleep we receive. In a study that observed 1,024 volunteers, those who received less than eight hours of sleep revealed reduced leptin and elevated ghrelin.[6] Leptin, an appetite suppressant hormone, and ghrelin, an appetite stimulant hormone, both play major roles in appetite. What an individual eats, therefore, is not just because of their willpower, or lack thereof. It also has to do with the amount of sleep they’ve been receiving. 

In recent years, research on inflammation has become increasingly popular. Inflammation has been cited as one of the main culprits for chronic illnesses such as rheumatoid arthritis, an autoimmune disease that can inflict inflammation and pain anywhere from joints to major internal organs.[7]

Research has also shown that sleep is linked to the inflammatory function of the body. Research has indicated that sleep triggers the body’s immune response, in which white blood cell count increases as a result of the body fighting off a foreign infection. 

Sleep is also correlated with the body’s circadian rhythm, which has been linked to many chronic diseases through the function of “clock-controlled genes”.[8] This concept is founded on the basis of the suprachiasmatic nucleus (SCN), an area of the brain that is considered the body’s “master circadian clock”.[8] The SCN consists of only 20,000 neurons — a small fraction compared to the brain’s total neuron count of 86 billion.[9] Located directly above the optic chiasm, which is responsible for vision, the SCN controls and synchronizes the body’s functioning via natural light. When an individual visualizes light, the SCN sends signals to other areas of the body, allowing the body to function. This is one of the reasons why humans’ cognitive function is at its best around late morning.[10] 

When sleep deficiency begins to take a toll on the body, inflammatory responses may arise, which may lead to a variety of unwanted illnesses. For example, a variety of studies have shown that sleep deficiency is highly correlated to asthma, with one study showing that insomnia is associated with the risk of developing asthma in 18,000 participants.[11] 

Tips for better sleep

The Center for Disease Control (CDC) has a few guidelines to help individuals develop better sleep habits. These habits include consistency, going to bed in a dark area, leaving distractions such as electronics outside of the bedroom, avoiding large meals right before bedtime, exercising during the day, and a slew of other healthy sleep-building habits that you can find on the CDC website.

References

[1] Okano, K., Kaczmarzyk, J. R., Dave, N., Gabrieli, J. D. E., & Grossman, J. C. (2019). Sleep quality, duration, and consistency are associated with better academic performance in college students. npj Science of Learning, 4(1), 16. doi:10.1038/s41539-019-0055-z

[2] Ellenbogen, J. M., Payne, J. D., & Stickgold, R. (2006). The role of sleep in declarative memory consolidation: passive, permissive, active or none? Current Opinion in Neurobiology, 16(6), 716-722. doi:https://doi.org/10.1016/j.conb.2006.10.006

[3] Dinges, D. F., Pack, F., Williams, K., Gillen, K. A., Powell, J. W., Ott, G. E., . . . Pack, A. I. (1997). Cumulative sleepiness, mood disturbance, and psychomotor vigilance performance decrements during a week of sleep restricted to 4-5 hours per night. Sleep, 20(4), 267-277. 

[4] Yoo, S.-S., Gujar, N., Hu, P., Jolesz, F. A., & Walker, M. P. (2007). The human emotional brain without sleep – a prefrontal amygdala disconnect. Current Biology, 17(20), R877-R878. doi:10.1016/j.cub.2007.08.007

[5] Guadagni, V., Burles, F., Ferrara, M., & Iaria, G. (2014). The effects of sleep deprivation on emotional empathy. J Sleep Res, 23(6), 657-663. doi:10.1111/jsr.12192

[6] Taheri, S., Lin, L., Austin, D., Young, T., & Mignot, E. (2004). Short Sleep Duration Is Associated with Reduced Leptin, Elevated Ghrelin, and Increased Body Mass Index. PLOS Medicine, 1(3), e62. doi:10.1371/journal.pmed.0010062

[7] Bullock, J., Rizvi, S., Saleh, A. M., Ahmed, S. S., Do, D. P., Ansari, R. A., & Ahmed, J. (2018). Rheumatoid Arthritis: A Brief Overview of the Treatment. Medical principles and practice : international journal of the Kuwait University, Health Science Centre, 27(6), 501—507. https://doi.org/10.1159/000493390

[8] Comas, M., Gordon, C. J., Oliver, B. G., Stow, N. W., King, G., Sharma, P., Ammit, A. J., Grunstein, R. R., Phillips, C. L. (2017). A circadian based inflammatory response — implications for respiratory disease and treatment. Sleep Science and Practice, 1(1), 18. doi:10.1186/s41606-017-0019-2

[9] Ono, D., Honma, K.-i., Yanagawa, Y., Yamanaka, A., & Honma, S. (2019). GABA in the suprachiasmatic nucleus refines circadian output rhythms in mice. Communications Biology, 2(1), 232. doi:10.1038/s42003-019-0483-6

[10] Valdez P. (2019). Circadian Rhythms in Attention. The Yale journal of biology and medicine, 92(1), 81—92.

[11] Brumpton, B., Mai, X. M., Langhammer, A., Laugsand, L. E., Janszky, I., & Strand, L. B. (2017). Prospective study of insomnia and incident asthma in adults: the HUNT study. Eur Respir J, 49(2). doi:10.1183/13993003.01327-2016