Number + も

Number + も is used to emphasize something by implying it would be surprising or extreme to experience, have, or do that amount or quantity. It often appears with negative verbs or adjectives to express 'not even this much' or with verbs/adjectives to stress how long, frequent, or extents something is. Common patterns include using a time or quantity before も (e.g., 一日も, 二時間も, 三回も) to underline that the speaker is highlighting the unexpected or surprising extent. Note that in many cases the nuance is stronger when paired with a negation (e.g., 一日も眠れない) or a strong verb/adjective.