The show returned this week for its fifth season and the actor told Metro: "One of the larger themes of the show is happiness and what it takes to achieve it, and that is a central irony.
"This is a man who ostensibly sells happiness yet is pretty dissatisfied with his own life."
He added: "I think that is one of his goals, though, to be happy and to find out what in his life will help him achieve true happiness.
"Monogamy is another goal. He is going to explore that to the extent he can."
Of Draper's complicated background, Hamm added: "There is a lot of his past still to be mined and there's a great deal we haven't found out - and a lot of that gets explored this season.
"It is constantly surprising to me and fun to peel back another layer of the onion and see who Don is and where he is going."
Last month, Hamm said that he perhaps shares a "misplaced childhood sense" with Draper, while also admitting that the character is "a coward".
Mad Men season five premiered on AMC on March 25. It returns to Sky Atlantic in the UK tonight (March 27) at 9pm.
> Mad Men exec Matthew Weiner: 'Don Draper is genuinely in love'
> Mad Men Don Draper poster reveals clues to season five - picture
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