Do the hour labels include the time it takes to fall asleep?

The hour line is the cycle count times 90 minutes. The fall-asleep setting moves the clock time and stays out of that hour line.

What time does Sleep now use?

Sleep now sets "go to bed at" to the current time, rounded to the nearest five minutes, with seconds included in the rounding. It then builds the same six lengths.

Can this tell me how long I slept last night?

It has no sleep log. It turns a time you enter into six possible lengths, from 1.5 hours to 9 hours.

Sleep time calculator

The sleep time calculator is about duration. Choose a time to be in bed, and the six cards show how long each option lasts and what clock time that makes in the morning. The hours come from the cycle count. The clock time and the fall-asleep offset are the parts you change.

What time should I wake up?

If you go to sleep at 8:00 PM, enter it as go to bed at 8:00 PM. The calculator adds the default 15 minutes to fall asleep, then the cycles. Each wake-up time below is where that sum lands.

6 cycles, 9 hours: 5:15 AM
5 cycles, 7.5 hours: 3:45 AM
4 cycles, 6 hours: 2:15 AM
3 cycles, 4.5 hours: 12:45 AM
2 cycles, 3 hours: 11:15 PM
1 cycle, 1.5 hours: 9:45 PM

Sleep time

Sleep time is the length of those cycles, not the wake-up clock. Each hour line is the cycle count times 90 minutes, and the fall-asleep minutes stay off that line.

6 cycles: 9 hours
5 cycles: 7.5 hours
4 cycles: 6 hours
3 cycles: 4.5 hours
2 cycles: 3 hours
1 cycle: 1.5 hours

From 11:00 PM with the starting 15-minute offset, the 7.5-hour card is a 6:45 AM wake-up, the 9-hour card is 8:15 AM, and the 1.5-hour card is 12:45 AM. The offset is time in bed before that sleep length starts.

Sleep now is the shortcut when the bedtime is "right now". It rounds the current time to five minutes and calculates as "go to bed at". To count the same lengths backward from an alarm, switch the control to "wake up at", or open the bedtime calculator, which starts in that mode.