Final answer:
Adolescents do require more than eight hours of sleep, which aligns with the National Sleep Foundation's recommendations and the findings of studies that suggest a mean of 8.9 hours among teenagers.
Step-by-step explanation:
The question asks whether it is true that adolescents need to get more than eight hours of sleep. Based on the information provided, adolescents do indeed require a substantial amount of sleep for optimal health and functioning. Specifically, the National Sleep Foundation has updated its recommendations to accommodate individual differences, emphasizing that different age groups have varying sleep needs.
Considering the study mentioned in the question saw a mean of 8.9 hours of sleep among teenagers and another study indicating sleep needs decline with age, it suggests that adolescents generally need more than eight hours of sleep for proper restoration and to avoid sleep debt, which could affect alertness and mental efficiency. Therefore, the answer to the question is A. True.