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year
age; years
past one's prime; old age
「歳」 has other readings with different meanings.
歳を重ねるのは早い。
The years go by fast.
歳をとると朝が早くなる。
You tend to wake up early as you age.
歳をとると朝が早くなるそうです。
They say you wake up earlier as you get older.