Periodic Limb Movement Disorder (PLMD): This condition is characterized by periodic episodes of limb movements during sleep, which can lead to fragmented sleep and daytime hypersomnia. The movements can disrupt sleep quality, resulting in excessive daytime sleepiness.

Restless Leg Syndrome (RLS): Although primarily known for causing discomfort and an urge to move the legs, especially in the evening, RLS can also disrupt sleep patterns. This disruption can lead to inadequate sleep and, consequently, hypersomnia during the day.
Sleep Apnea: This condition involves pauses in breathing or periods of shallow breathing during sleep, leading to poor sleep quality and daytime sleepiness.
Narcolepsy: A neurological disorder that affects the brain's ability to regulate sleep-wake cycles, often causing excessive daytime sleepiness.

Hypothyroidism: Although not directly related to sleep disorders, hypothyroidism can cause fatigue and excessive daytime sleepiness. Missing this diagnosis could lead to prolonged suffering and potential complications if left untreated.
Anemia: Similar to hypothyroidism, anemia can cause significant fatigue, which might be mistaken for hypersomnia. Identifying and treating the underlying cause of anemia is crucial.

Kleine-Levin Syndrome: A rare disorder characterized by recurring periods of excessive daytime sleepiness, often accompanied by automatic behavior and confusion. It's essential to consider this in the differential diagnosis due to its unique presentation and potential for misdiagnosis.
Idiopathic Hypersomnia: A rare neurological disorder that causes excessive daytime sleepiness without any identifiable cause, often resembling narcolepsy but without cataplexy.