Should choose a jam with lots of restrictions. For example, the only restriction on this jam is the timelimit. It's aimed more at people who are applying knowledge they already know, and work they have already done. Your game won't be as grand by design, but you'll learn more for time spent if you apply your own sets of restrictions when you enter jams like this. In that case, the aspect you lose out on is comparing yourself to others, thus the first point.
I'd honestly be curious who is planning to restrict sleep under 7 hours to work on this jam. The only valid reason I can think of for that is if you are very experienced and want to test just how big a game you can make in the timelimit. I see nothing but detrimental effects for people otherwise. Sleep deprivation is seriously scary when you learn just how important it is for your health, esp during a pandemic...you shouldn't think of it as 'I'll heal after', ur twisting the metal of a bridge...it may solidifies but remains bent.