Scarlett finds that she needs more than the 8 hours of sleep recommended for adults. If she gets less than 10 hours of sleep per night, she has difficulty concentrating, is forgetful, has problems driving, and cannot work effectively. Scarlett would most likely be diagnosed with:

The answer is hypersomnolence.

Explanation:

Hypersomnolence is a condition in which a person experiences a sense of sleepiness or exhaustion, even when they had the recommended amount of sleep time (around seven hours).

This disorder can affect a person's life in area such as school or the workplace. The symptoms usually appear in adolescence, and they have been linked to stress and other disorders like depression. Hypersomnia is often treated with stimulants (e.g. amphetamine).