"A Night in Sickbay" was first aired in the United States on the UPN network on October 16, 2002. It received Nielsen ratings of a 3.9/6 percentage share among all adults, including 6 percent of all adults watching television at the time of the broadcast. Although overnight figures had shown a slight decrease from the previous episode, the final numbers showed that the ratings were the highest seen so far during season two and the third week of increased ratings for "Enterprise" in succession. This meant that 6.26 million viewers watched the episode, an increase of 860,000 viewers from the previous week's episode, making it the highest viewed episode since season one's "". Alexander Chase at "USA Today" said the numbers "confirm a ratings turnaround for the newest Trek series". The episode placed "Enterprise" fourth in a list of the most highly rated science fiction/fantasy shows on television for that week, behind "Alias", "Smallville", and "John Doe".