There are several reasons for anal swelling at night: First, it may be due to enlarged, congested hemorrhoids or repeated prolapse of internal hemorrhoids, which to some extent irritates the skin mucosa around the anus. Second, it may be caused by women’s gynecological diseases. When women suffer from vaginal prolapse or uterine prolapse, some patients may experience anal swelling. Third, it may be caused by anal sinusitis, because the special location of the anal sinus is prone to bacterial accumulation and inflammation, in serious cases will appear anal swelling, pain. In addition to the above-mentioned cases, there may be perianal abscesses, intestinal inflammation caused by, if the feeling of swelling is strong, it is recommended to go to the hospital in a timely manner.