Do deaf people sleep better?
Let's firstly differentiate deafness - profoundly impaired ability to hear, and other states where the subjects can still hear at different degrees.

Secondly, differentiate the congenital deafness &amp; infantile hearing loss and hearing loss in adults who previously had normal hearing. 

The subjects with congenital and very early infantile hearing loss would have better sleep characteristics (this state will affect psychological state in a lesser degree than one acquired in more mature &amp; "conscious" state), while persons who have lost their normal hearing would have abnormal sleep patterns at least in the period when they have just realized that they are going to lose their hearing. After this "preliminary" period, the sleep pattern should be dependent on the person's psychological status and other similar factors.

Many persons will mention that while using ear plugs they feel that their sleep is better comparing with "un-plugged" sleep. 

sources


Characteristics of sleep in deafness. Rev Neurol. 1998 Jun;26(154).
Non-scientific source. 


Please pay attention that scientific sources are scarce, thus take the answer as one of limited evidence.