Sleep Mode

Sleep Mode or Easy Sleep Mode is a standby feature that allows the system to reserve battery power without turning it off or losing the game's progress. This function is useful for players who wanted to take a break in the middle of the playing session for a short while.

The Sleep Mode option for is present in certain Game Boy Advance titles. In Metroid Fusion and Metroid: Zero Mission, pressing the L button on the map screen will bring up the Sleep Mode screen. In the Classic NES Series port of Metroid, the Sleep Mode option can be selected from the Menu screen. Activating Sleep Mode will turn off the screen and sound while still retaining the game's progress. The game will resume from Sleep Mode if the L, R and Select buttons are pressed simultaneously.

With the Nintendo DS, closing the system activates Sleep Mode, and opening it will resume the game. This can also be done with the Nintendo 3DS.

Metroid Fusion manual
"From this screen, you can access Sleep Mode. This mode allows you to conserve battery life without turning the game off. The Sleep Mode function is convenient when you want to take a short break, but aren't near a Save Station."

Metroid: Zero Mission manual
"Easy Sleep allows you to conserve battery life without turning the power OFF. Easy Sleep is useful for when you want to take a short break but aren't near near a Save Room."

Classic NES Series: Metroid manual
"The power remains ON, but the liquid crystal display will turn off and the game will pause to reduce battery consumption."

Metroid Prime Hunters manual
"If you close your Nintendo DS during a game, it will go into Sleep Mode to save battery life. Open the DS again to resume the game."