Sleep Apnea: Morning headaches, particularly those that are bilateral and temporal, are a common symptom of sleep apnea. The condition is characterized by pauses in breathing during sleep, leading to poor sleep quality and subsequent morning headaches. The "fog" described could be related to the sleep disturbance and hypoxia associated with sleep apnea.

TMJ (Temporomandibular Joint Disorder): TMJ disorders can cause headaches, especially in the temporal region, due to the referred pain from the jaw joint and surrounding muscles. Morning jaw clenching or grinding during sleep could exacerbate symptoms, leading to morning headaches.
Tension-Type Headache: These are common and can occur bilaterally, often described as a band or a squeezing sensation around the forehead, which could be interpreted as temporal. Morning headaches could be due to tension built up during sleep or poor sleep posture.
Migraine: Although migraines are typically unilateral, some individuals may experience bilateral pain. The "fog" could be an aura or part of the migraine spectrum, and migraines can be triggered by sleep disturbances.

Hypertension: Severe, uncontrolled hypertension can cause morning headaches due to the increase in blood pressure during the night. Although less likely, it's crucial to rule out given the potential for serious complications.
Brain Tumor: Although rare, a brain tumor could cause increased intracranial pressure, leading to morning headaches. The "fog" might be related to increased pressure or tumor effects on brain function.
Subarachnoid Hemorrhage or Other Vascular Issues: Sudden, severe headaches (often described as "the worst headache of my life") can occur due to vascular issues. While the described headache doesn't fit the typical "thunderclap" headache, any sudden change in headache pattern warrants investigation.

Idiopathic Intracranial Hypertension (IIH): Characterized by increased intracranial pressure without a detectable cause, IIH can lead to morning headaches. It's more common in obese women of childbearing age.
Sleep-Related Eating Disorder: Although not directly causing headaches, this disorder involves eating during sleep, which could lead to morning headaches due to the physical act of eating or the consumption of certain foods.
Hypnic Headache: A rare condition characterized by recurrent headaches that occur only during sleep and wake the patient, typically in the early morning hours. The headache can be bilateral and is not associated with other neurological symptoms.