Bradbury has stated that one of the reasons he wrote the story/book Fahrenheit 451 (published in 1953) was because he had fears about trend of censorship in America in the early 1950s. Prior to this, there were book burnings in Nazi Germany in the 1930s; this censorship was part of a greater program of indoctrination and genocide perpetrated by the Nazis prior to and through World War I.
In America, in the early 1950s, Joseph McCarthy went on a crusade against anyone who might entertain or be associated with Un-American activities. More specifically, McCarthyism was a movement to find and eradicate any communist influences in America; this was during the Cold War. To reactionary people like McCarthy, anyone who embraced communist or Un-American ideas was the enemy. In both cases, Nazism and McCarthyism, censorship led to wrongful prosecution and limitation of thought (with Nazism leading to one of the worst genocides in human history). With McCarthyism, one of the effective promotions was to be a hardworking American, one who conformed to certain ideals of what an American should be. This can get away from innocuous patriotism to political repression and nationalism - at the expense of free speech and thought.
Bradbury was also commenting on the role of technology in reading literature. Televisions were becoming more common in American households in the 1950s. The more time one spends watching television, the less time they have to interact with other people and the less time they have to read. Bradbury clearly portrays television as an opiate, something that pacifies people, namely Mildred, into being thoughtless, conforming citizens. Mildred refers to the parlour (basically, a flat-screen television), as her "family." Mildred is so focused on her technological devices (the parlour and Seashells) that she is cut off from the world.
Montag notices this separation more as he begins to question his society. Mildred also takes sleeping pills, often overdosing, to escape from the world. Bradbury frames the dangerous potential of technology in suppressing thought and human consciousness via the parlours, Seashells, the Mechanical Hound, and the literal opiate of sleeping pills. When Montag considers the possibility that Mildred might die of a sleeping pill overdose, he is struck at the lack of emotion he thinks he would feel.
And he remembered thinking then that if she died, he was certain he wouldn't cry. For it would be the dying of an unknown, a street face, a newspaper image, and it was suddenly so very wrong that he had begun to cry, not at death but at the thought of not crying at death, a silly empty man near a silly empty woman, while the hungry snake made her still more empty.
The elements of censorship and technological pacification of human thought and interaction are themes common to the novel and what was going on in America (and other places) during the time Bradbury wrote Fahrenheit 451.