When you look at the tab on your journal that is shaped like a chest, do you notice that one of the stats (among others like fame, population, labor, etc) is beds? If you have more population than available beds, then when the simulation runs all the people who couldn't sleep will deteriorate in mood. Usually to grim, uncertain, numb, determined and brusque. You then have to work hard to get these people happy again, especially if you're following my infinite resources guide. Say you have a sleeping area (not bunks but just the tier 1 area) then you have a 50% chance that each person who can't find a bed will remain happy. Obviously that means 50% chance that the person will become sad.
I am currently experimenting with keeping my population equal to or below 16 beds and I'm being sure to always build a bunkhouse along with built in beds to achieve this. While trying this method out I've been playing at Alamo and/or savini's. I find that I can quickly gather the resources I need and keep my people happy very easily. In fact, I'm starting to wonder if you are guaranteed materials if every member of your little society is in a good mood. Last night when I logged off with 10 happy people, three of them made "finds" for materials. So even though I have zero material outposts I ended up making 5 materials for the night. If this is true then I'm only going to need food/ammo outposts for long term survival with a small group.
Who cares if Lilly keeps telling me I don't have enough people haha.
I'm thinking about creating a video of myself playing a level on breakdown. As of this writing I'm on 39, so maybe the big 4... 0... will be a good time to do it!