Coziness

Coziness, or sometimes called referred to as Comfiness, improves the effect of the buff gained from sleeping.
Coziness is a point-based stat that is granted by various deployables around the player. 
Items such as trophies, rugs, statues, furniture (tables and chairs), lights, and others can each grant a certain number of "coziness" points when the item is within 20 meters (approximately 7 "tiles", including vertically) of the player.
When the player sleeps, the total amount of Coziness that applies to the player in bed will be calculated and shown to increase both the effectiveness and duration of the Well-Rested buff.
The maximum effect from Coziness is reached at 700 points, which corresponds to an increase in duration of 385% and an increase in effectiveness of 175%.
The Well-Rested buff can also be modified by washing hands at the sink (+15% effectiveness) and by perks earned through the bestiary (up to 10% duration and 10% effectiveness).
The standard "well rested" buff has a duration of 600 seconds and, at 100% effectiveness, grants:
* +10% to maximum health and health regen
* +5% to maximum stamina and stamina regen
* -5% to food and water consumption rates
If the player uses the carved wood bed or equivalent (120% effectiveness, 700 seconds duration), washes hands before sleeping, and has completed the bestiary, then the maximum possible Well Rested duration is 3465 seconds, and the maximum effectiveness is 320%.
The MXC Cot from the Workshop has a lower effectiveness buff but 800s duration, which raises the total possible duration to 3960s but has a lower effectiveness of 310%