That’s what alarms are for. You go back to sleep and your alarm will wake you up.

In my opinion it’s always worth trying to go back sleep if you’ve got an alarm.

Speaking for myself, there’s nothing worse for falling back asleep than looking at the time. When I wake at night and it’s dark, it might be 11pm, 2am, or 5am. I don’t want to know what time it is. I go back to sleep and unless it happens to actually be within minutes of my alarm, I’ll fall back asleep and never know what time it was.

Exactly so. "Do I have time to get another hour or two of sleep, or is it time to get up and make coffee?"

I was thinking of building a touch-operated clock for that. Some sort of dongle with a single button that would vibrate the hour and quarter-hours like a church bell.

You could keep it under your blanket so you wouldn't need to move all that much to check the time.