Behavioral Economics please help.

Suppose there are three periods: bedtime, 8am and 9am. The agent has an exam at 9am the next day, and an alarm clock that can be turned off or can be set/reset only for 8am or 9am. The decision tree describes the actions available in each period: At bedtime she can either set the alarm for 8 or 9 or she can choose not to set an alarm. At 8am her possible actions are getting out of bed at 8am, resetting the alarm for 9am, or unplugging the alarm clock. At 9am her actions are getting out of bed at 9am or to unplug the alarm clock.

In this setting, a plan is a sequence of actions. For instance, (reset for 9, wake up at 9) is a possible plan available to the 8am self, which describes an action for her, and an action for the 9am self. Suppose the agent's preferences over plans at each point in time are fully dictated by her preferences over when to wake up: at bedtime, she prefers getting out of bed at 9am to getting out of bed at 8am to skipping the exam altogether; at 8am, she prefers getting out of bed at 9am to getting out of bed at 8am to skipping the exam; at 9am, she prefers to skip the exam over getting out of bed.

Need help drawing a decision tree given information on possible actions at each moment.