Yes, it helps to lessen the battery used by certain apps by "sleeping" them.
Sleeping apps will run in the background occasionally. You'll still receive notifications, but they may come late. Deep sleeping apps will never run in the background so you may not receive notifications at all when you add them here, unless you open the app.
Exlcuded apps from sleeping are sent in Never Sleeping apps. This prevents the AI/or you from adding some apps automatically to the Sleeping and Deep Sleeping app list.
By sleeping apps, you're limiting the drain they are causing when you're not using them, thus saving more battery power.
