Sleep mode slowly raises your air conditioner's set temperature after you go to bed, usually by about 2 to 4°F over the first one to four hours, so the room does not get colder than you need. Some units also lock the fan on low or switch off at the end. The exact schedule differs by brand, so check your manual.
Sleep mode on an air conditioner slowly raises the set temperature after you go to bed, usually by about 2 to 4°F over the first one to four hours, so the room does not get colder than you need while you sleep. Some units also drop the fan to low, and some switch off at the end of the cycle. Use it when you start the night comfortable and wake up cold; skip it if the room already struggles to stay cool.
How sleep mode works
Sleep mode is a short program, not a new way of cooling. The unit still runs in Cool (or Heat), but it nudges your set point in steps on a timer. In cooling it moves the set point up. In heating, on units that heat, it moves it down.
The size of the steps, the timing and what happens at the end differ by brand and even by model. These are the schedules the manuals we opened give.
Room air conditioners (window and portable)
Frigidaire's room air conditioner sleep mode page gives the fastest schedule we found. The set temperature goes up 2°F 30 minutes after you press Sleep, then another 2°F 30 minutes later. The unit holds that new temperature for 7 hours, then goes back to the temperature you first chose.
GE's APCD06 and APCD08 portable manual runs slower. The set temperature rises 2°F (1°C) after 2 hours and another 2°F after 2 more hours. GE also says the fan runs at Low and cannot be adjusted while sleep mode is on, and a Sleep indicator lights. The APCD10 and APHD10 manual says the same.
Ductless mini splits
Midea's US split system owner's manual raises the set temperature 2°F (1°C) after 1 hour in Cool, then another 2°F after another hour. In Heat it lowers it by the same steps. The sleep feature stops after 8 hours, and the system keeps running at the final setting rather than switching off.
Senville's LETO owner's manual uses the same two one-hour steps, but the ending differs. It holds the new temperature for 5 hours, then the unit turns off on its own.
Fujitsu ties sleep to a timer you set. Its ASU9RL and ASU12RL manual says that in Cool or Dry the thermostat setting rises 2°F every 60 minutes until it has gone up 4°F in total. It holds there until the time you set runs out, then the unit stops. In Heat it drops 2°F every 30 minutes, to a total of 8°F. Fujitsu says the point is "to prevent excessive warming or cooling during sleep."
Daikin's FTX30 and FTX36NVJU operation manual has no Sleep button at all. Instead, setting the OFF timer turns on what Daikin calls NIGHT SET mode. It raises the set point by only 0.9°F (0.5°C) in Cool and lowers it 3.6°F (2.0°C) in Heat, to prevent too much cooling or heating during sleeping hours.
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The schedules side by side
| Brand and model | What happens in Cool | When it ends |
|---|---|---|
| Frigidaire room air conditioners | Up 2°F after 30 minutes, up 2°F more after another 30 minutes | Holds for 7 hours, then returns to your original setting |
| GE APCD portables | Up 2°F after 2 hours, up 2°F more after another 2 hours; fan locked on Low | Not stated; press Sleep or Mode to cancel |
| Midea US split systems | Up 2°F after 1 hour, up 2°F more after another hour | Sleep stops after 8 hours; the unit keeps running |
| Senville LETO | Up 1°C (2°F) after 1 hour, up 1°C more after another hour | Holds for 5 hours, then the unit turns off |
| Fujitsu ASU9RL, ASU12RL | Up 2°F every hour, 4°F in total | The unit turns off when the timer you set runs out |
| Daikin FTX30, FTX36NVJU | Up 0.9°F once, when the OFF timer is set | The unit turns off at the OFF timer |
So two units that both say "Sleep" can behave quite differently by 3 a.m. One may be 4°F warmer than you set, another under 1°F. If you want to know exactly what yours does, the Sleep section of your own manual is the only reliable answer.
When to use sleep mode and when not to
Sleep mode suits you if you set the unit cool to fall asleep and then wake up cold, or if you keep getting up to turn the temperature up. It does the adjusting you would otherwise do by hand.
Skip it, or pick a higher starting point, in these cases:
- Your bedroom stays hot all night and the unit already runs hard to keep up.
- You like the room at one steady temperature until morning.
- You want the unit off by morning, but your model keeps running (Midea) or returns to the original setting (Frigidaire).
Two limits come up in several manuals. Midea, Senville and MrCool all say sleep is not available in Fan or Dry mode; MrCool's mini split remote manual notes it can only be turned on from the remote. And on units where sleep is tied to an off timer (Fujitsu, Daikin), using it means the unit will shut off at the time you choose.
If the room cannot reach a comfortable temperature even without sleep mode, the unit may be too small for the space. Our room size calculator shows the BTUs a room needs, and our guide to an AC that will not cool below 75 covers the common causes.
How to turn sleep mode on
Set the mode (Cool or Heat) and the temperature you want at bedtime first. Then turn sleep on. Three of the remotes we checked work like this.
GE portable (APCD series)
- Press the Sleep button. The Sleep indicator lights.
- To cancel, press Sleep again or press the Mode button.
Fujitsu (ASU9RL, ASU12RL)
- Press SLEEP while the unit is running or stopped. The green Operation lamp and orange Timer lamp on the indoor unit light.
- To change the run time, press SLEEP again and use the Timer Set buttons while the display flashes (about five seconds).
- To cancel, use the Timer Mode button to select CANCEL.
MrCool and Midea split remotes
- Press SET (or the Sleep button if your remote has one) and scroll until the Sleep symbol flashes.
- Press OK to confirm. Repeat the same steps to turn it off.
MrCool's remote manual and Midea's owner's manual both describe this SET and OK sequence. If your remote has its own Sleep button, MrCool says you cannot pick sleep through SET.
Other brands and remotes differ. Check your own manual for the button name and the schedule. For the other buttons on the same remote, see our guide to AC modes.
Does sleep mode save energy
Several makers say it does, and none we checked put a number on it. MrCool and Midea describe sleep as a way to decrease energy use while you sleep. Fujitsu and Daikin frame it as preventing too much cooling or heating overnight. We found no maker figure for how much it saves, so we do not give one.
A higher set point in summer means less cooling work. ENERGY STAR's room air conditioner advice is to set the thermostat as high as is comfortable, typically 78°F. Sleep mode moves you a few degrees in that direction during hours when you are not awake to notice. How much that saves depends on your unit, your starting temperature and how long the program runs.
If you want to see what your unit costs per night, our cost to run calculator works it out from the unit's wattage and your state's rate. Pair sleep with the right fan setting too: see fan mode on an AC and quiet mode if noise is what wakes you.
Frequently asked questions
Does sleep mode turn the air conditioner off?
It depends on the model. Senville's LETO holds the raised temperature for 5 hours and then turns off. Fujitsu and Daikin tie sleep to a timer, so the unit stops when the time you set runs out. Midea's split systems keep running at the final setting after 8 hours, and Frigidaire room units return to your original temperature after the 7-hour hold.
How much does sleep mode raise the temperature?
Most manuals we opened raise the set point by 2°F in each of two steps, for 4°F in total. Frigidaire does it within the first hour, Midea and Senville over two hours, and GE portables over four hours. Fujitsu also stops at 4°F in cooling. Daikin's NIGHT SET mode is the gentlest, raising the set point by only 0.9°F.
Can I use sleep mode with dry mode or fan mode?
On many units, no. Midea, Senville and MrCool all say the sleep function is not available in Fan or Dry mode. Fujitsu is an exception for Dry: its manual says the thermostat setting rises during Cooling or Dry operation when the sleep timer is set. Check your own manual, since this varies by model.
Does sleep mode make the air conditioner quieter?
Only on some models. GE's APCD portable manuals say the fan runs at Low and cannot be changed while sleep mode is on, which lowers airflow noise. Most mini split manuals we checked describe only the temperature change. If noise is the problem, a quiet or silence setting is the more direct fix, where your unit has one.
Founder of Home Caprice. Ben started the site to simplify HVAC after dealing with the heating and cooling in his first apartment.