Heat stroke is on the rise and is expected to account for 2.5 more deaths by the year 2050. For the first time, scientists have been working on learning if being exposed to sunlight for long periods of time can affect your cognition—and the results are in from the University of Copenhagen.
To mimic the amount of heat generated from working outside under the sun, heat radiation lamps were positioned around the eight male adult participants while they took motor-cognitive tests. The lamps were positioned at their backs, sides, and overhead. The tests took place on computers and focused on subjects such as math tasks or logic tests with a particular emphasis on tasks that required fine motor accuracy.
The computer tests weren’t the average math test; participants were using pinching movements on a device, attached to a load cell connected to an amplifier, instead of a computer mouse. For one portion of the test, there was a number on the screen that represented how hard they needed to pinch the load cell. For another test, the participants did calculations; and in another math test, they were asked to calculate the sum of four numbers by either typing the result or using the pinch gauge. Other tests included visuomotor tracking.
The body temperature and deep core temperature was measured while the participants took the tests under the heat radiation lamps. There were no cognitive impairments discovered when exposure to heat radiation on the lower body occurred, coinciding with a rise in temperature. The real insight came with the investigation when they focused on the heat directed at the head.
When the head was exposed to heat, skin temperature of the head increased but did not raise deep core body temperature. The effect of direct heat stress on the head caused a sharp decline in cognitive function on the motor-cognitive tests. The takeaway from this study is that when the head is exposed to heat radiation, the effects on cognition and a deterioration in function occurs at a much lower body temperature than previous studies on the principles of hyperthermia stated.
Previous studies did not fully investigate the radiative heat exposure effect, and this new research showed that the cognitive and motor declines occurred at 38.5 degrees Celsius (a full degree cooler than the previous assumptions) . Now the study authors are hoping to bring awareness of the effects heat causes on cognition for those who are working outdoors performing cognitively demanding tasks, especially in the construction, agriculture, manufacturing, transportation, and tourism industries.
Piil, J.F., Christiansen, L., Morris, N.B. et al. Direct exposure of the head to solar heat radiation impairs motor-cognitive performance. Sci Rep 10, 7812 (2020). https://doi.org/10.1038/s41598-020-64768-w