Turn off Automatic Sleep Mode
In Apple Menu > System Preferences > Energy Saver set Computer Sleep to Never.
Make sure “Put hard disks to sleep when possible” is NOT checked.
(These settings may vary on different Mac Models)
This will mean that Sleep Mode does not come on automatically, but you can still put your computer to Sleep when you like, by going to Apple Menu > Sleep.
This is one of the most important steps to prevent problem behavior with an audio device because Sleep Mode works by suspending drivers in a hibernate state, rather than unloading them fully. When waking up the computer does not “enumerate” the drivers fresh as with a newly connected device, but just attempts to proceed as if nothing changed.
However your Audio Device will think it has been disconnected during Sleep, as the driver was no longer available. During Sleep the unit may shut off or go into a standalone mode depending on it’s model/design/features. When the computer wakes from Sleep the Audio Device doesn’t receive a good connection because the driver is not reloaded fresh as with a true unplug/replug, called “driver enumeration.”
Automatic Sleep can lead to situations where you get up for a quick break during your session and come back to glitchy audio, artifacts, no audio, a full disconnect, and other performance issues. Very short Sleep Mode settings, such as every 1 minute, can even create situations where you turn to do something in the studio like adjust your outboard mixer and before you are done the whole unit has been disconnected, or an erroneous firmware message has popped up.
If you must use Sleep Mode, then for best performance first turn off/unplug your interface and then choose Sleep from the Apple Menu. When you come back to work you can Wake the computer and then plug in/power the interface and get a freshly loaded driver.