Suspend is fast. State lives in RAM.
RAM needs power.
The battery drains.

Hibernate preserves sessions. It stores them on disk.
It's slower - but it removes the pressure from the battery.

The best of both worlds:

• The system suspends.
  
• A timer is started.
  
• When the timer expires:
  
  • The system wakes up.
    
  • It hibernates to swap.
    
• On power-on: it resumes from swap.
  

• The swap > RAM.
  
• The initramfs contains libs to read LVM and LUKS.
  

Find the swap UUID:

sudo blkid | grep swap

On encrypted systems, the resume target must resolve to the unlocked swap device provided by initramfs.

Add the UUID as resume option to GRUB in /etc/default/grub:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash resume=UUID="

Apply the change:

sudo update-grub

If the swap is on LUKS:

echo RESUME=UUID= | sudo tee /etc/initramfs-tools/conf.d/resume
sudo update-initramfs -u
sudo reboot

Test the hibernate and resume:

sudo systemctl hibernate

Suspend-then-hibernate is a wrapper. If hibernate is broken, the wrapper cannot save it.
The system must hibernate and resume correctly.
If it fails - repair this function first.

Edit systemd sleep configuration in /etc/systemd/sleep.conf:

[ Sleep]
 AllowSuspend=yes
 AllowHibernation=yes
 AllowSuspendThenHibernate=yes
 HibernateDelaySec=30min

Manually test it:

sudo systemctl suspend-then-hibernate --no-block

--no-block returns control to the shell immediately; it does not bypass suspend or hibernate inhibitors.

The system suspends.
After 30 minutes it wakes up and hibernates.

If it fails, debug:

journalctl -u systemd-suspend-then-hibernate
journalctl -b | grep -i hibernate

This setup is:

• systemd-native
  
• Stable across updates
  
• Suitable for encrypted systems
  
• Tested on Intel ThinkPad platforms
  

No scripts. No hacks. No legacy ACPI glue.

[ Fear the Silence. Fear the Switch. ]