The question is under what conditions can we overuse our brain? To be concrete lets focus on mental tasks like coding and math problem solving.
Q1: How many hours of "fun"(i.e. stressfree) problem solving can we do in a day (say out of 14 waking hours)?
Here are some interesting studies/posts
- Focal dystonia this is from an answer in Quora: "To go a little off topic, it may be possible to damage your brain through overuse, but more from years and years of repetitive practice. Ironically, the very skill you spend so much time developing is the part that gets disrupted. This is a disease called focal dystonia—”Focal dystonia most typically affects those who rely on fine motor skills (musicians, writers, surgeons, etc.)"
- How Being a Workaholic Differs from Working Long Hours: "We found that work hours were not related to any health issues, while workaholism was. "
- Excessive brain activity linked to a shorter life: "I think this is overactivity, out-of-control excitation — it’s not good for the brain. You want the neurons to be active, when and where you want them to be active, not to be just generally firing off,"
- Does Thinking Really Hard Burn More Calories?: "The brain continuously slurps up huge amounts of energy for an organ of its size, regardless of whether we are tackling integral calculus or clicking through the week's top 10 LOLcats."
- What cognitive processes occur during a mental exhaustion or 'burnout'? : "One of the older theories suggested that a person literally runs out of brain-fuel when they hit the wall (Baumeister et al, 1998). They called this state "ego depletion" and it refers to the kind of mental burnout you are talking about."
Q2: Any comments on the above studies/posts as it regards the goal of estimating the hours of safe but intense mental activity? Can we infer anything from them to help with that estimation?
Based on these studies, I think the answer is 10-12 hours but given that
- we vary the tasks to avoid "focal dystonia"
- maintain a healthy lifestyle (sleep,exercise, diet)
- and most importantly try to keep the work enjoyable.