Graphic by Maia Brown

Welcome back to Northwestern! While you were enjoying the summer sunshine, scientific research and discoveries continued here on campus. Check out the summer Research Recap to stay up-to-date on what’s new in the science field.


Sudden exposure to bright light at night will not interfere with the normal sleep/wake cycle of your body. Diesel cars in the emissions scandal affected children’s health, causing lower birth weights and increasing asthma in children. Northwestern professor researched for accurate data on gun violence.

Checking your phone in the dark will not change your overall sleep/wake rhythms

You wake up in the middle of the night. You try, but you just can’t go back to sleep. Then you reach out for your phone to pass time and see if you can get sleepy. However, you find that the more you stare at the bright screen, the harder it is to fall back to sleep. You start to wonder: Will light at night change my sleep/wake cycle and have some effects on my body?

Scientists have long believed that light information at the wrong time of the day would change the body’s sleep/wake rhythms. They thought that all light information goes through the same pathway and processes in the same area of the brain, whether it is natural light or a sudden burst of strong artificial light. If this is the case, then even slight exposure to light would probably affect your sleep/wake rhythms. Some researchers, including Northwestern’s professors Tiffany Schmidt and Fred Turek, found out that our brain allows long-term and short pulses of light to go from different pathways. As a result, short exposure to acute light will not run the risk of shifting the sleep/wake cycles.

These Northwestern researchers studied a genetically modified mouse model that only had the previously-believed single pathway and area in the brain to process all light information. Mice have reverse sleep/wake cycles – they wake at dark and sleep when exposed to light. Scientists provided short pulses of light to mice in the dark and observed that they stayed awake and did not respond to the light. They also checked the mice’s body temperatures, which should change depending on whether the mouse is awake or asleep, and found out that their body temperatures remained the same after exposing to the short pulses of light. This evidence showed that acute light at dark did not shift the mice’s sleep/wake cycles and further supported that the light-response system has multiple pathways.

For now, scientists still need more information to map out those pathways. They still do not know which part of the brain processes the short pulses of light. Once researchers find out more about the light-processing procedure of the brain, they can use their research to help those who need to be alert when exposed to light, such as nurses and emergency personnel, without leaving some harmful effects on their health.

Pollution from diesel cars involved in the emissions scandal caused population-level health impact

In September 2015, the United States Environmental Protection Agency (EPA) issued a notice of violation of the Clean Air Act to Volkswagen. The EPA found out that Volkswagen’s “clean diesel cars” cheated on emissions testing to pass the U.S. regulations. Those cars emitted a severely high level of pollution, much higher than gasoline-powered cars. Northwestern’s Professor Hannes Schwandt, along with other researchers in the U.S., wanted to know how this additional pollution affected the health of the population, especially children.

The researchers tracked the data based on where the diesel cars ended up and checked the pregnancy and birth information in those places. They found that about 38,600 children had lower birth weights because of the additional pollution. They also saw an increase in asthma in young children. They calculated a 2% increase in fine particulate matter – a pollutant known to impair population health – a nearly 2% increase in the rate of low birth weight for each of those diesel cars per 1,000 cars, and an 8% increase in asthma emergency room visits for children.

This research is the first to show that vehicle pollution affects people who are not living near the highway or in low-income communities. It discussed how this pollution from diesel cars affected the entire population, with a special focus on those with high socioeconomic backgrounds. The “clean diesel cars” attracted mostly environmentally conscious consumers with higher income because the company emphasized the car’s low emission level.

Researchers plan to expand the study to older children, adults and the elderly population to gain a full picture of the health effects of those cheated diesel cars.

Available gun violence data underestimated the actual number of gun shootings

There is no existing single data source that captures the full picture of gun-related injuries in the United States. This lack of information concerned Northwestern’s Professor Lori Ann Post. She and researchers from Yale University and the University of New Haven published their study “Bolstering gun injury surveillance accuracy using capture-recapture methods” in August to discuss the true prevalence of gun violence in the U.S.

Professor Post and other researchers looked up gun violence data from law enforcement, emergency departments, emergency medical services, media and medical examiner records. The number of cases covered in those records varied, and none of them had an accurate number of all gun-related injuries and deaths. The study focused on a small data set of gun violence cases from August 1, 2013, to December 31, 2013, in New Haven, Connecticut. Researchers then looked for the data overlap. They observed and counted the number of data sets in which an individual appeared.

Using the capture-recapture method, a method often used to estimate an animal population's size, researchers were able to estimate a more accurate number of gun incidents. The capture-recapture method’s logic is that a portion of the population is captured, marked and released. Later a second group is captured and the number of the marked individuals from the previous group is counted. Then we can calculate the estimated population size because the number of marked individuals within the second sample should be proportional to the number of marked individuals in the whole population.

Using this method, researchers were able to get a more accurate number of gun incidents, which is higher than any available data set. They estimated that 49 gun injuries occurred within the defined geography. However, the highest number of gun injuries/deaths recorded in an existing data sample was 43.

Professor Post pointed out that we need to fully understand gun violence’s frequency and its patterns in order to have effective policies to prevent gun-related injuries and deaths.