Table of Contents
People who work in emergency medicine and provide fire-prevention services, medical internships and residencies as well as other high-stress jobs, are usually needed to work 24-hour shifts with very little opportunity available for sleep. It is known that extreme fatigue can affect many emotional, cognitive and physical processes and can cause stress hormone secretion, increased inflammatory processes and increased blood pressure. What isn't known is how these 24-hour shifts, that lead to sleep deprivation, affect the functioning of the heart.
It was important to investigate whether any negative health-related effects were associated with too much work and not enough sleep, since people seem to work longer hours or at more than just one job in order to make ends meet. Researchers then decided to conduct a first-of-its-kind study to investigate what the immediate effects of a 24-hour shift, associated with sleep deprivation, had on the health of people.
For the purposes of this study, researchers enlisted 20 radiologists who were healthy and not known with any acute or chronic conditions. These radiologists included 19 males and one female, with an average age of around 32 years. The participants weren't allowed to consume caffeine-containing products, as well as not being allowed to take in food and drinks containing theobromine (which is found in tea, nuts and chocolate).
Each of these test subjects had cardiovascular magnetic resonance (CMR) imaging performed on them (in order to determine cardiac contractility), with strain analysis done before and after a 24-hour shift that included an average of 3 hours of sleep. The test subjects also have blood and urine samples taken from them, as well as having their heart rates and blood pressures measured and monitored.
A limitation of the study was that researchers didn't take into account factors such as environmental stimuli and the individual's own stress levels.
When all the relevant investigations were performed and the data was collected and analyzed, the following findings were made.
- There was an increase in systolic and dialstolic blood pressures of around 6% and 11%, respectively.
- The heart rate in these individuals had increased by 8%.
- Peak systolic circumferential strain, which represents heart contractility, had increased slightly.
- The test subjects' thyroid functions had shown increased levels of thyroid stimulating hormone (TSH) as well as the thyroid hormones T3 and T4. There were also increased levels or cortisol, which is a hormone released by the body as a response to stress.
The clinical significance
The findings made in this study seemed to be short lived, therefore the researchers stated that further studies needed to be performed in a larger population group in order to determine whether there were any long-term affects of sleep deprivation. The findings in these studies would then help health care professional better understand how shift duration and workload would affect public health.