Putting an Imac that boots from USB SSD to sleep

[Mac Hammer Fan]

My friend had an iMac 2015 that boots under Mojave from an external USB 3.0 SSD (Crucial). APFS formatted.
Is it safe to put his iMac to sleep instead of shutdown and restart? (to avoid random lockups at startup)

 

[ProteoMX]

Should be perfectly fine (as long as he keeps the drive connected, of course).

 

[chscag]

Yes, it should be safe. SSDs don't really sleep anyway since there are no moving parts as there are in a spinning hard drive. My iMac has an internal SSD and it sleeps okay, but in reality it's probably only the display and the fan that turns off.