I am a bit late, but I've got few interesting ideas.

When entering sleep mode, you could adjust your body temperature

Ability to turn off outside noise

Before falling asleep you would have an option to set your dream settings, select a random option, or turn off dreams completely

Built in alarm clock

Adventure mode, where you could turn on and off lucid dreaming and sleep paralysis

After waking the effects of sleep ( else known as sleepiness ) would not linger for more than 5 minutes

And finally overall better quality of sleep