Sometimes, dietary deficits are connected to oversleeping. Iron deficiency is the most prevalent, and since it lowers blood oxygen delivery, it can lead to weariness and poor energy. Cognitive slowness, weakness, and severe fatigue are other symptoms of vitamin B12 insufficiency. Mood swings and exhaustion have been linked to low vitamin D levels. In certain instances, folate insufficiency also plays a role. But rather than being a result of a lack, oversleeping is frequently linked to thyroid issues, depression, sleep apnea, or persistent stress. Despite using stimulants such as Modvigil 200, chronic fatigue may still be caused by underlying inadequacies.