Alertness refers to being fully awake and observant. It means being aware of one's surroundings and paying attention to what is happening. Full definition
It requires courage, wisdom, timing, focus, and an incredible sense of alertness of everything happening around you. (christianitytoday.com)
The resume of a truck driver mostly highlights the physical skills, mental alertness of the driver as well as his expertise in driving the huge vehicle safely. (template.net)
In a study funded by NASA, David Dinges, a professor at the University of Pennsylvania, and a team of researchers found that letting astronauts sleep for as little as fifteen minutes markedly improved their cognitive performance, even when the nap didn't lead to an increase in alertness or the ability to pay more attention to a boring task. (businessinsider.com)