1. A first, researchers successfully combined video monitoring and EEG to quantify mental fatigue.

2. Visual signs of mental fatigue include changes in eye blinking rate and pupil diameter.

3. Repetitive thinking is often a precursor to depression due to mental fatigue and depletion of melatonin.

4. Important differences are that the presence of mental fatigue is necessary to fulfill the criteria and symptoms are accepted that may suggest a psychiatric disorder.

5. One Muzak-associated exec asserted to The Seattle Times: "Research demonstrates that music prolongs the alertness of workers, relieves mental fatigue resulting from monotony and boredom, Alleviates worry and keeps the mind from dwelling on petty grievances" (Squire).