Hypersomnia or Excessive Daytime Sleepiness: This condition is characterized by an inability to stay awake and alert during the day, which aligns closely with the symptoms described. It can be due to various factors including sleep disorders, medication side effects, or neurological conditions.

Sleep Apnea: A condition where breathing stops and starts during sleep, leading to poor sleep quality and excessive daytime sleepiness.
Narcolepsy: A neurological disorder that affects the brain's ability to regulate sleep-wake cycles, causing sudden attacks of sleep or drowsiness.
Medication Side Effects: Certain medications, such as sedatives, antidepressants, or antihistamines, can cause drowsiness as a side effect.
Depression: Some forms of depression can lead to excessive sleepiness or fatigue.

Stroke or Transient Ischemic Attack (TIA): Although less common, a stroke or TIA can present with sudden changes in alertness, including drowsiness.
Intracranial Hemorrhage: Bleeding within the brain can cause alterations in consciousness, including periods of drowsiness.
Meningitis or Encephalitis: Infections of the brain or meninges can lead to changes in mental status, including drowsiness.
Diabetic Coma or Hypoglycemia: Severe blood sugar imbalances can cause alterations in consciousness, including drowsiness.

Kleine-Levin Syndrome: A rare disorder characterized by recurring periods of excessive daytime sleepiness, often accompanied by automatic behavior.
Idiopathic Hypersomnia: A rare condition similar to narcolepsy but without cataplexy, characterized by excessive daytime sleepiness.
Prion Diseases: Rare, fatal brain diseases that can cause changes in sleep patterns among other neurological symptoms.
Wilson's Disease: A genetic disorder that leads to copper accumulation in the brain, which can cause neurological symptoms including changes in sleep patterns.