Adding total work hours based on list of timestamp submissions

Hi all,

I'm sure this is easy, but I'm exhausted and am having trouble "formulating" a plan here:

Employee submits forms at leisure, in sporadic groupings, 24/7.

I've pulled the submission date/time data for the pay period.

I've highlighted groups of rows that I want to add the hours/minutes worked.

Then, I'll want to add the hours/minutes of all the groupings, to get a total amount of hours to pay them.

What format should I make the date/time stamp, and which formula(s) should I use to make this easier?

Example of default list:

See, I want to add the time worked from 11:13pm to 12:03am and from 3:38pm to 4:46pm, together.

Of course, not adding the time from midnight to 3pm as worked.

I'm sorry, I'm so tired, that I don't think I can even properly explain my puzzle.

I'll post in case I make sense to someone... and I'll revisit after a nap.

Thanks in advance,

- Tony