A self-reported daily life note (LN) is an effective tool used by occupational physicians to assess the capacity of workers on sick leave due to mental illness to return to work (RTW). We aimed to clarify whether there were differences in the criteria used to define recovery for RTW between LN users and non-users, whether LN users were satisfied with LN, and whether non-users wanted to use LN. In total, 363 occupational physicians (238 LN users, 125 non-users) completed self-reported questionnaires covering demographic and occupational variables, and RTW assessment criteria. We investigated which of the 10 assessment criteria were considered most important for RTW. The proportion of LN users was higher among women, younger physicians, and occupational physicians with more working days per month. LN users emphasized four criteria in assessing RTW: 1) constant wake-up time, 2) constant bedtime, 3) no midnight waking, and 4) no feeling of drowsiness during the day. LN users regard regular sleep rhythm and the absence of drowsiness during the day as important criteria for RTW. Ninety-seven percent of users regarded LN as useful. Seventy-four percent of non-users had interest in using LN.