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Sleep Modes in Linux

Overview​

Linux offers two main sleep modes: s2idle (Suspend-To-Idle) and deep (Suspend-To-RAM).

  • s2idle is always available and provides basic power savings.
  • deep offers greater power savings but requires hardware and firmware support.

How to Check Supported Sleep Modes​

To see which sleep modes your laptop supports, run:

cat /sys/power/mem_sleep

Typical output:

[s2idle]

If only s2idle is listed, your system is currently using Suspend-To-Idle.

Enabling Deep Sleep​

On many modern laptops, enabling "deep" sleep may require a BIOS/UEFI change. Look for a Linux-specific sleep or ACPI setting in your firmware setup.

After enabling the correct BIOS option and rebooting, you may see:

[s2idle] deep

This means both modes are available, but s2idle is active.

To switch to deep sleep, run:

echo deep | sudo tee /sys/power/mem_sleep

Now, the output will show:

s2idle [deep]

The brackets indicate the active mode. With "deep" selected, Suspend-To-RAM will use the deeper sleep state.

Summary​

  • Check available sleep modes with cat /sys/power/mem_sleep.
  • Enable "deep" sleep in BIOS/UEFI if needed.
  • Select "deep" mode with echo deep | sudo tee /sys/power/mem_sleep.
  • Enjoy improved battery savings when suspending your laptop.

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