This issue was fixed in March 2015
My Sim has a negative moodlet each morning from not playing enough video games. Even without having the nerd trait.
This issue has nothing to do with the nerd trait (although that can of course also cause the moodlet – just not every morning). The cause of this is the Mod Pod Twin Sleeper. For some obscure reason the bed causes the moodlet since Patch Dec 2014.
Use a different bed.