Author Archives: Sara Djondovic

Repetitive Negative Thinking Leads to Less Sleep

Posted on March 19, 2018 | 2 comments

Sleeping cat. Image courtesy of: Emanuele Spies on Flickr

Have you ever woken up in the middle of the night unable to sleep because you are worrying about your future and you continue to think about the worst possible scenarios? No matter the reason, we all get negative thoughts once in a while and these thoughts can lead to less sleep than the required 7-9 hours for adults from ages 18 to 65. Researchers have found that people who sleep less than 8 hours a night are more likely to suffer from depression and anxiety.

Rumination is the act of repetitively dwelling on thoughts that cause anxiety and distress. Your brain cycles through problems without solving them and when this happens, it can lead to negative thinking. This is especially dangerous for people who are depressed or anxious because it is difficult to switch perspectives and look for solutions to the problems. Thus, rumination intensifies and so do anxiety and depression.

This year, researchers found that a shorter sleep duration is related to the difficulty of disengaging individuals from rumination. Jacob Nota and Meredith Coles at Binghamton University, conducted a study with 52 community members from ages 18 to 65 with heightened repetitive negative thinking and varying sleep durations. Of the 52 participants, 50% of them met the criteria for major depressive disorder, 44.2% met the criteria for generalized anxiety order, and 36.5% met the criteria for social anxiety disorder; some participants fit multiple categories.

Figure 1: Schematic of how Nota and Coles conducted the attention task. Seventy-eight trials were done.

They showed the participants positive (e.g. nature scenes) or negative (e.g. guns, knives) images paired with a neutral (e.g. household items) image. When the participant fixated on one image, researchers put the other image in a frame to direct the eyes and track eye movement as shown in Figure 1.

On average, 92% of the time, participants would look at the negative image first when paired with the neutral image. When the positive image was paired with the neutral image, participants would look at the neutral image first. Participants were also, on average, 79% slower disengaging from the negative image when paired with the neutral image as shown in Figure 2.

Figure 2: Average percent of participants that would engage with a type of image first and average percent of participants that would slowly disengage from a type of image.

After asking participants about their habitual sleep duration, 96% of those with a shorter sleep duration spent more time looking at the negative image than the neutral image and had difficulty fixating on the neutral image compared to the negative image.

Despite this interesting discovery, researchers are still evaluating how the timing and duration of sleep may contribute to the development of depression and stress. Further research can then allow psychologists to treat anxiety and depression by adjusting their patients’ sleep cycles to a healthier time.

Want to know more about negative thinking and how to stop it to get a good night’s rest? Check out the video above!

– Sara Djondovic

References

  1. Bergland, C. (2015). The Brain Mechanics of Rumination and Repetitive Thinking. Psychology Today. Retrieved March 18, 2018 from https://www.psychologytoday.com/blog/the-athletes-way/201508/the-brain-mechanics-rumination-and-repetitive-thinking.
  2. Binghamton University. (2018). People who sleep less than 8 hours a night more likely to suffer from depression, anxiety. ScienceDaily. Retrieved March 18, 2018 from www.sciencedaily.com/releases/2018/01/180104152947.htm.
  3. Gura, L. [Actualized.org]. (2014). Negative Thoughts – The Origin Of Negative Thinking & How To Eliminate It Forever. Retrieved March 19, 2018 from https://youtu.be/mggupbkTmWc.
  4. N. A. (n.d.). How Much Sleep Do We Really Need? National Sleep Foundation. Retrieved March 18, 2018 from https://sleepfoundation.org/excessivesleepiness/content/how-much-sleep-do-we-really-need-0.
  5. Nota, J. A. & Coles, M. E. (2018). Shorter sleep duration and longer sleep onset latency are related to difficulty disengaging attention from negative emotional images in individuals with elevated transdiagnostic repetitive negative thinking. Journal of Behavior Therapy and Experimental Psychiatry. 58, 114-122. https://www.sciencedirect.com/science/article/pii/S0005791617300629.
  6. Wehrenberg, M. (2016). Rumination: A Problem in Anxiety and Depression. Psychology Today. Retrieved March 18, 2018 from https://www.psychologytoday.com/blog/depression-management-techniques/201604/rumination-problem-in-anxiety-and-depression.

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Practice Testing: Prevent Stress from Affecting Your Memory

Posted on February 26, 2018 | 2 comments

Figure 1. Studying student. Image courtesy of: Skokie Public Library on Flickr

Round two of midterm exams is approaching fast and before you know it, it is final exam season. This can cause a lot of stress for students, so how can you increase your marks before the end of the school year? Researchers have found that practice testing as a learning strategy can protect your memory from the negative effects of stress.

No matter how many exams a student has written in their life, they can still get stressed hours before writing an exam. When you are stressed, it is difficult to retrieve information from your memory because your body is preparing for a flight or fight response. The best way to prevent stress from affecting your memory is to study effectively.

Most students tend to study by re-reading the textbook and re-writing notes; this is known as study practice. Another method of studying involves taking practice tests to study for an exam; this is known as retrieval practice.

In 2016, researchers at Tuft University conducted an experiment with 120 students comparing the learning strategies of retrieval practice versus study practice. Participants were asked to learn 30 nouns presented as words and 30 nouns presented as images. This was done using a computer program which displayed an item for a few seconds. Then participants typed a sentence including the item displayed to simulate note taking.

Half of the participants were put into the study practice group and the other half in the retrieval study group. The participants learning by study practice had the items re-displayed multiple times on the computer. The participants learning by retrieval practice took timed practice tests where they had to recall as many items as possible.

For both learning strategies there were non-stressed and stressed participants. Half of the participants from each learning strategy were put under stress conditions and the other half in non-stress conditions. Stress conditions were created by having participants give a speech or solve difficult math problems in front of a group 24 hours after studying.

The memory test for stressed participants was taken during the stressful task to accurately represent the feelings of most students before a test. The non-stressed group took the memory test during a non-stressful task. The participants were asked to accurately recall as many items possible.

Figure 2. Average number of words and images accurately recalled immediately after stress.

As seen in Fig. 2, retrieval practice is the best way of studying because participants in stressful situations recalled the same number of items as participants in non-stressful situations. With this learning strategy, stress had little to no effect on the number of items recalled. The stressed retrieval practice group also recalled more items than the non-stressed study practice group.

Why is retrieval practice effective? The learning strategy forces you to recall information repeatedly and this helps strengthen long-term memory retention. So, for your upcoming exam, try studying through retrieval practice to handle the stress and ace your exam!

Want to know more about retrieval practice? Check out the video above!

– Sara Djondovic

References

  1. Agarwal, P. K. [Retrieval Practice]. (2017). Retrieval Practice Overview. Retrieved February 25, 2018 from https://www.youtube.com/watch?v=ZO8abw3DHxs&feature=youtu.be.
  2. Agarwal, P. K. Retrieve!. Retrieval Practice. Retrieved February 25, 2018 from https://www.retrievalpractice.org.
  3. McLeod, S. A. (2010). Long-term memory. Retrieved February 25, 2018 from www.simplypsychology.org/long-term-memory.html.
  4. N.A. (n.d.). The fight or flight response: Our body’s response to stress. Young Diggers. Retrieved February 25, 2018 from http://www.youngdiggers.com.au/fight-or-flight.
  5. Segal, J., Smith, M., Segal, R., Robinson, L. (2018). Stress Symptoms, Signs, and Causes. HELPGUIDE.ORG. Retrieved February 25, 2018 from https://www.helpguide.org/articles/stress/stress-symptoms-signs-and-causes.htm.
  6. Smith, A. M., Floerke, V. A., Thomas, A. K. (2016). Retrieval practice protects memory against acute stress. Science, 354(6315), 1046-1048. http://science.sciencemag.org/content/354/6315/1046.
  7. Tufts University. (2016). Practice testing protects memory against stress. ScienceDaily. Retrieved February 24, 2018 from www.sciencedaily.com/releases/2016/11/161124160426.htm.

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Human Adaptation to High Altitudes

Posted on January 15, 2018 | Leave a comment

Tibetans. Image courtesy of: reurinkjan on Flickr

Have you ever climbed up a mountain and found it more difficult to breathe as you got closer to the summit? Tibetans do not have this problem because they have a gene that makes it easy for them to live at high altitudes. They got this gene from an extinct species of human known as Denisovans.

At high altitudes, people get altitude sickness because of the thinner air. When the body is unable to get the oxygen it needs, you start to breathe faster. Symptoms such as headache and loss of appetite start to appear and remain until your body gets used to the elevation change. Tibetans, however, are able to live at altitudes above 4,000 meters. They never experience altitude sickness despite having less hemoglobin in their blood than the average person.

In 2010, researchers found several genes that give Tibetans the ability to efficiently use low concentrations of oxygen. One gene, known as EPAS1, causes the regulation of hemoglobin production. The EPAS1 gene was sequenced from 40 Tibetans and 40 Han Chinese because they were once part of the same population 2,750 to 5,500 years ago. Emilia Huerta-Sánchez and colleagues found all of the Tibetans and two of the Han Chinese had a segment identical to the EPAS1 gene. The researchers searched genome databases and were unable to find anyone living with the same gene.

With no one living available, they compared the gene with sequences from extinct humans such as Denisovans and Neanderthals. There was a match with the Tibetan gene and Denisovan gene. Researchers checked that Tibetans got the gene from Denisovans by looking at sequenced genes from different parts of the world. They found that Tibetans inherited the gene in the last 40,000 years from Homo heidelbergensis, who passed the gene onto modern humans and Denisovans.

The evolution and geographic spread of Denisovans compared to Neanderthals and modern humans. Image courtesy of: John D. Croft on Wikipedia

Emilia Huerta-Sánchez and colleagues found that Tibetans and the Han Chinese got the EPAS1 gene by mating with Denisovans. This was possible because modern humans were not the only existing humans at the time. Denisovan fossils were found among modern human and Neanderthal fossils showing that all three species interacted with each other.

So why did all forty of the Tibetans sequenced have the EPAS1 gene, but only two of the forty Han Chinese have it? The gene was not beneficial for the Han Chinese because they did not settle in high altitude areas like Tibetans so they lost the gene over time. However, Han Chinese have been found to mate with Tibetans which is why the gene is still found in some of them. The gene was beneficial for Tibetans and through natural selection, the gene proliferated among their population causing their ability to thrive in high-altitude environments.


Want to know more about how Denisovans and Neanderthals relate to the modern human? Check out the video above!

– Sara Djondovic

References

  1. Davis, C. P. Hemoglobin (Low and High Range Causes). MedicineNet. https://www.medicinenet.com/hemoglobin/article.htm. Published November 8, 2017. Accessed January 13, 2018.
  2. Gibbons, A. Tibetans inherited high-altitude gene from ancient human. Science. http://www.sciencemag.org/news/2014/07/tibetans-inherited-high-altitude-gene-ancient-human. Published July 2, 2014. Accessed January 13, 2018.
  3. Healthwise Staff. Altitude Sickness. HealthLinkBC. https://www.healthlinkbc.ca/health-topics/ug3357. Published May 7, 2017. Accessed January 13, 2018.
  4. Huerta-Sánchez, E. et al. 2014. Altitude adaptation in Tibetans caused by introgression of Denisovan-like DNA. Nature. 0: 1-4.
  5. N.A. EPAS1 gene. U.S. National Library of Medicine https://ghr.nlm.nih.gov/gene/EPAS1. Published January 9, 2018. Accessed January 13, 2018.
  6. Wee, R. Y. Who Are The Han Chinese People? World Atlas. https://www.worldatlas.com/articles/who-are-the-han-chinese-people.html. Published April 25, 2017. Accessed January 13, 2018.

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