Feeling Tired? Scientists Use Brain Scans to Measure Fatigue

Yawning in the middle of the day is completely normal for people with hectic schedules. How do you know whether it’s a sign to grab a cup of coffee or a red flag of an underlying condition? Why do people with depression, multiple sclerosis, and other neurological conditions often feel exhausted throughout the day? Researchers believe they finally have the tools to answer these questions thanks to a newly developed method for measuring feelings of fatigue.

In a research paper published in Nature Communications, professor Vikram Chib, from the Johns Hopkins University School of Medicine and colleagues conducted a study to objectively quantify how tired people feel.

“We know the physiologic processes involved in fatigue, such as lactic acid build-up in muscles, but we know far less about how feelings of fatigue are processed in the brain and how our brain decides how much and what kind of effort to make to overcome fatigue,” said Chib.

After training to recognize an effort scale, a cohort of 20 adult participants was asked to hold and apply pressure to a sensor in repeated trials until they became fatigued. They then were given two choices: a coin flip which randomly assigned an effort level for the next round, or a set effort level. The uncertainty associated with the “risky” choice allowed…