What role do sleep debt and circadian misalignment play in mood disorders among early adults, and how can light exposure be used diagnostically or therapeutically?

What role do sleep debt and circadian misalignment play in mood disorders among early adults, and how can light exposure be used diagnostically or therapeutically?

• A. They have no impact on mood; light exposure is not used.
• B. They contribute to mood symptoms; morning bright light can shift circadian phase and improve mood; light therapy is used as treatment.
• C. Sleep debt improves mood; light exposure worsens mood.
• D. Mood disorders cause sleep debt but light has no effect.

Answer: (B)