Lack of sleep, stress can lead to symptoms resembling concussion
Stress resilience is one of the most important things when it comes to knowledge work, also one of the most neglected aspect. Mindfulness, stoicism, exercise help, but nothing helps as much as a good night sleep. Also the other thing people usually fail to note is the vicious stress-sleep cycle (lack of sleep induced stress  stress induced lack of sleep). It took me years to realize that so much of my problems with bedtime revenge, burnout, non-clinical depression, permastress was basically just lack of quality sleep. FWIW, it helps to think of productivity in terms of sleep and stress when you are working in the knowledge economy. Just like sleep debt, you can also accumulate productivity debt due to lack of stress resilience, lack of sleep, which can eventually lead to things like burnout.