What causes muscle weakness and sleepiness?

Narcolepsy?: Some patients have narcolepsy and cataplexy. It is characterized by sudden and transient episodes of bilateral loss of muscle tone without loss of consciousness often triggered by an emotional stimulus such as laughter, surprise, anger, fear or humorous situations. Other reasons are sleep paralysis (weakness on awakening), what could be normal.

Diet and exercise: Many things can cause it ... But if you have a well balanced diet and regular exercise, muscles are stronger and sleep is better.