While Thursday night's Democratic debate on MSNBC was undoubtedly the fiercest and most personal yet - with Hillary Clinton and Bernie Sanders squaring off head-to-head for the first time - it was also by far the lowest-rated debate of the 2016 presidential cycle, according to preliminary Nielsen data reviewed by CNN.

Nielsen, which measures what consumers watch and buy, reports that the debate had a 3.3 household rating, averaging 4.5 million viewers during its 9 p.m. to 11 p.m. EST broadcast. That includes about 1.2 million viewers in the main news age group of 25-54, according to Variety. The prior low was ABC News' debate held the Saturday night before Christmas, which was watched by 8.03 million people, earning it a 6.0 household rating.

The previous Democratic debate, which aired on NBC on Jan. 17, averaged 10.16 million viewers and 3.2 million adults in the 25-34 age group – a 7.2 rating.

During Thursday's debate, MSNBC still led in ratings compared to other cable news networks but was no match for any of the major broadcast networks.

To be fair, MSNBC has less reach than most of the networks, and many viewers might not have been aware that the debate was even taking place, as it was scheduled and sanctioned by the Democratic National Committee at the last minute, and promotion didn't start until a few days prior, noted Politico.

However, the lower ratings could also indicate that Americans are simply burned out from too many debates. The last Republican debate, which didn't include front-runner Donald Trump, attracted the second-smallest audience of seven GOP debates. However, the 12.5 million who tuned in and the 8.4 rating is still far better than the numbers for the MSNBC democratic debate, according to Reuters.