Analytical function as argument

 Hi, I understand that analytical function cannot be used as an argument of aggregate function. But how can i achieve the following? Any workaround?

SELECT log_date, empl_code,
       sum((Lead(time_in,1,null) over(PARTITION BY log_date,empl_code ORDER BY time_in)-time_out)*24*60) in_between_time
  FROM time_logging
group by log_date, empl_code

Regards,
Sha