Problem

My sims mood is always red although all their needs are green and they only have positive moodlets

Cause

This is probably caused by the well-rested moodlet, which is bugged since Patch 1.18/2.13/3.9/4.6/5.4/6.1. The beds for which this moodlet is supposed to give less than +25 Mood, seem to actually make your mood worse, beds over +25 can have them have a constant good mood. Only the ones that give out +25 exactly seem to work correctly.

Workarounds

• Buy your sims good beds (use a cheat if you don’t have enough money, it’s not really cheating). The ones that give +25 are the best.
• Restarting your game seems to reset your mood
• Omit the well-rested moodlet

Mod that solves the problem

• Buzzler@MTS has made a HotFix Mod for this issue: Mood Hotfix