**A 9:30 bedtime could be a reasonable trial, depending on when she needs to wake up.** At age 12, the recommended sleep range is **9–12 hours**; at ages 13–17, it’s **8–10 hours**. Allow time to fall asleep when working backward from her morning alarm. [CDC sleep recommendations](https://www.cdc.gov/sleep/about/)

For example, if she wakes at 6:30 AM:

- 9:00 PM gives her 9½ hours in bed.
- 9:30 PM gives her 9 hours.
- 10:00 PM gives her 8½ hours.

Puberty can shift her body clock later, so her request is understandable. Starting high school alone isn’t a reason to move bedtime later; her wake-up time and sleep needs should guide the decision. [American Academy of Pediatrics](https://www.healthychildren.org/English/healthy-living/sleep/Pages/healthy-sleep-habits-how-many-hours-does-your-child-need.aspx)

You could agree together to try 9:30 for two weeks, provided it leaves enough sleep time. Keep the morning alarm consistent and notice whether she wakes reasonably easily and stays alert during the day. If mornings become harder or she’s regularly tired, move bedtime earlier again. That gives her some say and makes the decision something you can assess together.