“…Performance bias was unclear in every study because there was insufficient information about the timing of the assessments during the day. Detection bias was low in 27 studies (31-34, 37-39, 41, 42, 44-47, 49-52, 54-58, 61, 64, 66-68) and unclear in the remaining 11 studies because information about the measurement device was insufficiently reported(35,36,40,43,48,53,59,60,62,63,65). Attrition bias was rated "low" in 15 studies(38, 40, 43, 46-51, 54, 57, 59, 60, 65, 68), "unclear" in 16(31-35, 41, 42, 45, 52, 55, 61-64, 66, …”