Which condition could be indicated by nocturnal headaches or headaches in the morning?

A. Tension headaches are typically related to stress and do not have a specific pattern of occurring at night or in the morning. B. Sinusitis headaches usually worsen with sinus pressure and may be worse when bending forward, not specifically nocturnal or morning. C. Migraines often have variable timing and may not specifically occur at night or morning. D. Nocturnal or morning headaches can indicate increased intracranial pressure caused by a brain tumor or other space-occupying lesion, as pressure builds overnight and is relieved during the day.