Re: mental effects of diet - Likewise for dehydration. I try to keep a cup of water on my desk all the time now, or at least have a few ounces on each break.

Re: mental effects of diet - Likewise for dehydration. I try to keep a cup of water on my desk all the time now, or at least have a few ounces on each break. Also for me personally, it isn't listlessness necessarily. Sometimes I have boundless amounts of energy, but it's just not appropriate for the task I have at hand -- ex. working on a data structure & algorithms puzzle vs. writing a rest endpoint. In college, this was easy to circumvent because I had 100% control of what work I did at what time of day. I spent many nights during grad school working between 11 pm and 3 am (because I wanted to and it worked well for me).