Insufficient sleep (less than 6 hours) reduces workplace productivity by increasing absenteeism and presenteeism, resulting in approximately 6 lost working days per year compared to those sleeping 7-9 hours.

The empirical findings of this study suggest that workers who sleep less than six hours per day report on average about a 2.4 percentage point higher productivity loss due to absenteeism or presenteeism than workers sleeping between seven to nine hours per day... this means that a worker sleeping less than six hours loses around 6 working days due to absenteeism or presenteeism per year more than a worker sleeping seven to nine hours.