|“||There are only so many hours a Sim can go before needing a good night's sleep. Of course, a caffeinated beverage or quick nap can substitute in a pinch.||”|
— The Sims 3
In The Sims Social, this need was renamed to Sleep, possibly to avoid confusion with energy in that game.
Sims can replenish their energy by sleeping. Toddlers will awaken whenever their energy bar reaches 100%. If an older Sim's energy bar reaches 100% before midnight, the Sim will awaken when it becomes full. Otherwise, children, teens, young adults, and adults will usually sleep until 6:00 am (06:00) unless they are awakened earlier, though they will automatically wake up when their energy bar is at 100% if they have other actions queued up by the player. In addition, if Sims with full energy bars have autonomous reactions pushed on them, they may wake up. Elders who are asleep past midnight will usually awaken shortly after their energy bar reaches 100%. In The Sims 3, the player can drag the action handle to specify a time for the Sim to wake up.
If a Sim needs a quick boost of energy, they can drink coffee or espresso. Children cannot do this, but in The Sims 2: Seasons, they can get some energy by drinking hot chocolate from the Perfect Packets Hot Chocolate Maker. Sims can get coffee from a coffeemaker or an espresso machine, or buy an espresso from the espresso bar[TS:U][TS2:U][TS2:AL] while on community lots. Drinking coffee, espresso, or hot chocolate will decrease the bladder motive as a consequence, however.
Sims also gain a small amount of energy from sitting down.[TS] Sims can nap on lounge chairs, recliners, and sofas, but it doesn't replenish energy as effectively as sleeping in a bed, and active Sims may wake up before they're fully refreshed.[TS][TS2] In The Sims 3 and The Sims 4, Sims will automatically wake up from a nap after a few hours, with a moodlet that counteracts the effects of low energy.
Sims will pass out when they run out of energy. They will collapse onto the floor, or will fall asleep standing up if there is not enough room. In The Sims 2: University, a Sim who passes out while eating will fall asleep face-first into their food. Sims cannot pass out on community lots.[TS1][TS2] Sims cannot pass out while at work or school, but may do so as soon as they are finished. Like with most motives, Sims may refuse to perform certain interactions if they are too tired.
While Sims will not die from exhaustion, they can drown if they become extremely tired while in a swimming pool. They will normally get out of the pool autonomously before this happens unless they are prevented from doing so, such as by removing the pool ladder.
Equivalents for other life states
The Sims 2
For Servos[TS2:OFB], the equivalent of energy is Power. Servos can replenish this by sleeping or napping, the same as Sims can. If it's daylight, they can use the "Recharge" self-interaction to go outside and stand in the sun until their power is replenished. If they are in gold or platinum aspiration, they can also restore their power by using The Eclectic and Enigmatic Energizer or drinking the Elixir of Life. If the power need gets too low, a Servo will either go outside to recharge, or go berserk and require repairs by a Sim with high mechanical skill, preferably one with a gold talent badge in robotics.
For PlantSims[TS2:S], the need for sunlight has many aspects of the energy motive. If a PlantSim's sunlight need becomes too low during the day, the PlantSim will go outside to be in the sun. If the sunlight need becomes critically low at night, the PlantSim will go outside and collapse, and will revive after dawn the next day.
The Sims 3
Mummies[TS3:WA] do not have an energy motive at all, but move very slowly.
For plumbots[TS3:ITF], the equivalent of energy is Battery Power. A plumbot recharging station is available in Buy mode, and plumbots will recharge while turned off. Charging at a recharging station does not appear to be that pleasant however, as the plumbot will repeatedly twitch and sometimes bend down and put its hand to the side of its head as if in pain while charging. If a plumbot's battery power is completely drained, it will shut down. A plumbot with the Solar Powered trait chip will gain battery power while outdoors in daylight. Unlike Servos, plumbots can remain active while using solar power, but the chip may not always provide enough power to completely offset the power drain caused by whatever the bot is doing. Plumbots can syphon power from appliances, but at a cost to their maintenance need.
The Sims 4
For vampires,[TS4:V] the equivalent of energy is Vampire Energy. Vampires recharge vampire energy by sleeping in a normal bed, sleeping in a coffin, or dark meditating. Vampire energy is also used for vampire powers.
The Sims 3
|Image||Moodlet Name||Mood Effect||Time Period||From||Game Dialog/Description||Notes||EP|
|Sleepy||No Mood effect||3 Hours||Low Energy Need||Get (Sim Name) to bed soon, to avoid the wrath of the truly tired.||After the 3 hours, if the Sim doesn't sleep s/he will become tired. 4 hours for Babies and Toddlers.|
|Tired||-40||3 Hours||Very Low Energy Need||When Sims get too tired, their mood begins to go south.||After the 3 hours, if the Sim doesn't sleep s/he will become exhausted.|
|Exhausted||-50||Until Sleep||Critically Low Energy Need||At this level of sleep deprivation, even the floor looks like a good bed to this Sim.||Sim may pass out. (They can be woken up using an interaction on the Sim.) Can also be caused by a Moodlet Manager backfire.|
|Well Rested||+10-30||10 Hours||High Energy Need||It's easy to wake up on the right side of the bed when you got plenty of time in the bed.||Varies depending on the quality of the bed. +10 mood for each + in the catalog. There is a mood glitch associated with this moodlet, in which it gives a Sim a bad or good mood prior to patch 24.|
|Slow||No Mood Effect||3 Hours||Low Energy Need||Even the mighty vampire must sleep from time to time. Seek out a comfortable bed for restful slumber.||Vampires only; receive instead of "Sleepy". Changes to Lethargic after 3 hours.|
|Lethargic||-40||3 Hours||Very Low Energy Need||When Vampires grow too tired, their powers are nonexistent and their mood grows sour.||Vampires only; receive instead of "Tired". Changes to Drained after 3 hours.|
|Drained||-50||Until sleep||Critically Low Energy Need||At this level of energy a Vampire is powerless, worse than a normal Sim.||Vampires only; receive instead of "Exhausted". Vampires may pass out.|
|Slept Like The Dead||No mood effect, +10-30||10 Hours||High Energy Need||Vampires enjoy sleeping deeply, which is a fair trade off for the lack of a pulse.||Vampires only; receive instead of "Well Rested".|
The Sims 4
|Image||Moodlet Name||Effect||Emotion||Time Period||From||Game Dialog/Description||Notes||EP|
|Sleeping Soundly||10000||Asleep||Until Sim wakes up||Sleeping||ZZZzzzzzzzzzzzz...|
|Tired||1||Uncomfortable||3 Hours||Low Energy Need||(Sim Name) is Tired, and will need to rest soon.||Changes to "Exhausted" when timer expires.|
|Exhausted||3||Uncomfortable||3 Hours||Critically Low Energy Need||This level of sleep deprivation will make any Sim miserable!||Sim will pass out when timer expires.|
|Tired||1||Sad||Timer not shown||Low Energy||(Sim Name) is tired and will need to rest soon.||Angelic toddlers only.|
|Exhausted||3||Sad||Timer not shown||Critically Low Energy||This toddler is near passing out, it's time to get him under some covers for some much needed sleep.||Angelic toddlers only. Sim will pass out when moodlet expires.|
|Revitalized by Nap||1||Energized||6 Hours||Taking a Nap||Nothing revitalizes the body like a quick little cat nap.||Randomly appears. Does not appear on Lazy sims|