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The continued advancement of technological innovations has provided infinite possibilities in regards to what technology can be used for. In the past century alone, computers, mobile phones, television, microwaves, and the Internet were established. These technological implications resulted in a complete revolution of society. In the next few decades, the majority of the population will have never lived in a world where these technologies did not exist. Technologies such as these have become so easy to access, that the modernized world has begun to depend on them to function. Trends have shown that time spent staring at screens has been increasing at near-exponential rates. In fact, from the year 2006 to 2016, the average 12th grader in the United States had doubled their daily screen-time (Twenge, et al. 2018). Social media use has become increasingly prevalent, especially in those aged 18-24. By 2018, 78% of young adults from this age group used Snapchat, 71% used Instagram, and 45% used Twitter, many of which use more than one platform of social media (Smith and Anderson, 2018). Excessive time spent staring at screens is a relatively new concept. For this reason, the way the brain responds to screen usage is not well-understood.
Previous studies have suggested that increased screen time may harm both the psychological and physiological well-being of individuals, especially when observing adolescents. Copious amounts of screen time were found to be linked to poor self-control, emotional instability, anxiety, and depression (Twenge and Campbell, 2018). Screen-time has also shown a correlation to sleep patterns (Hale and Guan, 2015). This may be due to the effects that screens have on one’s melatonin levels, a hormone responsible for regulating circadian rhythms. When comparing melatonin levels before sleeping in E-book readers and traditional book readers, E-book readers actually had a decrease in melatonin levels (Edgar and Ranson-Olson, 2014). When melatonin levels are precarious, it can cause adverse effects on sleep quality.
Cortisol is a natural-occurring hormone produced by the adrenal glands. It assists with several bodily functions, including stress-response, blood pressure regulation, metabolism, and immune response. Although cortisol is helpful in the occasional dangerous situation, long-term release of this hormone has been shown to have negative consequences on the body (Lee, et al. 2015). This can affect activity in the hypothalamic-pituitary-adrenal (HPA) axis, a coordination system consisting of the adrenal glands, hypothalamus, and pituitary glands. It is vital in maintaining homeostasis as a negative feedback loop (Heaney et al. 2013). Imbalances of cortisol in the body due to problems with the HPA axis may cause Addison’s disease, caused by underproduction, or Cushing’s syndrome, caused by overproduction (Katsu and Iguchi, 2016). Cortisol levels can be measured through samples of blood, saliva, urine, and even hair. From these options, salivary cortisol is shown more useful in measuring unbound, biologically-active cortisol (Lee, et al. 2015). Additionally, saliva samples possess a vast array of benefits when compared to other methods. Saliva extraction is minimally invasive and easy to store, as it does not need to be frozen up to a week. Unlike blood extraction, salivary samples may be obtained without causing additional stress that could affect adrenocortical response. This aspect is important to take into consideration, as HPA axis stimulation instantly induces hormone secretion, usually only taking between 15 and 30 minutes to reach its peak (Keil, 2012).
One drawback of salivary cortisol measurements is that they fluctuate regularly throughout the day. As they are affected by the circadian rhythm, it is important to know that there is a spike in cortisol levels about a half-hour after initially waking up, and lower levels in the evening.Measurements can also be thrown off from food and sugary drinks consumed up to an hour before extraction. Caffeine and nicotine may cause cortisol levels to rise, as they stimulate adrenocortical response (Lupien, 2013). The half-life of caffeine is close to 7 hours, so consumption of coffee and energy drinks may affect cortisol levels for extended periods of time (Statland and Demas, 1980).Other than cortisol, additional psychological and physiological measurements may be indicators of stress. Perceived stress could be measured through surveys. Physical stress responses other than cortisol may be analyzed from blood pressure, body temperature, and Electroencephalograms (EEGs), which measure electrical activity in the brain (Hosseini and Khalilzadeh, 2010).
The objective of this study is to determine whether there is a correlation between the amount and type of screen-time and cortisol levels in young adults. Between cell phones, television, social media, and video games, the average person spends a large portion of their waking hours staring at a screen. Since salivary samples are a reliable source of biologically active cortisol, they will be useful in measuring acute stress-response (Lee, et al. 2015). Since technology has become such an important part of everyday life, it will be beneficial to how screen-time and screen-usage type affect adrenocortical response. A surplus of stress hormones, such as cortisol, can cause health complications and therefore influence well-being. For this reason, this study could show the relation between screen usage and health. If a correlation is be supported, additional research could be done, promoting change in a rapidly increasing, technology-based society.
A total of 76 individuals attending Lake Superior State University will be included in this study. Participation will be voluntary, and the volunteers will be recruited by verbal request in multiple class settings. This will be a two-part study including both a survey and physical examination. Each participant will be assigned a numerical code to link results from the two parts. This is intended to maintain the confidentiality of participants.
In order to qualify as a participant, one must meet the requirements and agree to various restrictions prior to testing. Participants must fall between 18-24 years of age and not be a smoker/e-cigarette user. They must also agree to avoid food and sugary drinks an hour before testing and avoid caffeinated beverages 7 hours prior as well. Approval for this study must be granted by the Institutional Review Board, as it will be dealing with human subjects. Participants will be made aware that they may withdraw from the study at any point in time.
Before the physical examination, participants will be asked to complete a written questionnaire. It will cover topics that may be beneficial in ruling out cofactors that also play a role in the adrenocortical response. Questions will cover topics such as average daily screen-time, most frequently used screen-type, perceived stress levels, perceived pain, household income, employment, relationship status, drug/alcohol use, weekly exercise, grade point average, interest in a study/major, number of credits, gender, sex, ethnicity, body mass index, nutrition, place of origin, pets, residence, and the average amount of sleep. Before and after the experiment, participants will also be asked to assess their mood on multiple 1-5 scales.
The physical exam will include measurements before and after the experiment, including cortisol levels, blood pressure, temperature. To measure cortisol, Salivette cotton swabs will be used to collect saliva samples. Two Salivary Cortisol ELISA kits will be required, as each kit is capable of 76 tests. The cotton swab will be placed in the mouth so that it can absorb unstimulated salivary production. Simultaneously, blood pressure and temperature will be recorded. These three measurements will be taken before and after screen stimulation. ELISA kits should be stored between 2-8 degrees Celsius, and all samples should be marked with the corresponding code. Physiological data should be obtained at consistent times of the day, to avoid effects from circadian cycles. Before swabbing, the mouth should be rinsed sufficiently with water. Pipettes and a centrifuge will be required to prepare these samples for immunoassay kits(ELISA kits).
The 76 people will be divided into two groups: computers and smartphones. The two groups will have access only to their designated type of screen for 30 minutes. Other devices may not be used during this time period, and participants should be utilizing their technology the entire time. Saliva extraction, blood pressure, and temperature will be taken immediately after the time has passed.
The possible correlation between cortisol levels and screen-time will be tested using a paired sample t-test. This will use the initial and final values recorded from each individual. This will help determine whether there is statistical significance regarding the two observations of cortisol levels, blood pressure, and temperature. ANOVA tests will also be useful in comparing cortisol levels with the additional variables. A Chi-Squared test should also be computed, using normal circadian-rhythm-related cortisol levels as a comparison.