Transient Global Amnesia (TGA): A sudden, temporary episode of memory loss that is often triggered by stress, physical exertion, or medical procedures. It is characterized by an inability to form new memories, while memories of events prior to the onset of amnesia remain intact.

Medication Side Effects: Certain medications, such as sedatives, antidepressants, and antihistamines, can cause memory loss as a side effect.
Sleep Deprivation: Lack of sleep or disrupted sleep patterns can lead to impaired memory and cognitive function.
Vitamin B12 Deficiency: A deficiency in vitamin B12 can cause memory loss, fatigue, and other neurological symptoms.
Hypoglycemia: Low blood sugar can cause confusion, disorientation, and memory loss.

Stroke or Transient Ischemic Attack (TIA): A sudden loss of memory, especially when accompanied by other symptoms such as weakness, numbness, or difficulty with speech, can be a sign of a stroke or TIA.
Subarachnoid Hemorrhage: A sudden, severe headache accompanied by memory loss and other symptoms can be indicative of a subarachnoid hemorrhage.
Meningitis or Encephalitis: Infections such as meningitis or encephalitis can cause sudden memory loss, fever, and other symptoms.
Seizure: Certain types of seizures, such as complex partial seizures, can cause sudden memory loss and other symptoms.

Creutzfeldt-Jakob Disease: A rare, degenerative brain disorder that can cause sudden memory loss, dementia, and other neurological symptoms.
Hashimoto's Encephalopathy: A rare condition characterized by inflammation of the brain, which can cause memory loss, confusion, and other symptoms.
Whipple's Disease: A rare, systemic bacterial infection that can cause memory loss, dementia, and other symptoms.
Korsakoff's Syndrome: A rare condition characterized by memory loss, confusion, and other symptoms, often caused by chronic alcohol abuse or malnutrition.