Sleep is related to Animal. Animal is related to Leather. Grain is a type of Leather. Grain is related to Fiber. 
Unhappy is a synonym of Low. Low is the opposite of Highway. Highway is related to Big. Big is related to River. 
Sleep <--RelatedTo--> Animal <--RelatedTo--> Leather <--IsA-- Grain <--RelatedTo--> Fiber 
Unhappy <--Synonym--> Low <--Antonym--> Highway <--RelatedTo--> Big <--RelatedTo--> River 