If I understand correctly you have a matrix with 2 rows, the first row shows times, and the second 1. You are asking to count how many ones between a certain time range.
Here is an example on how to do this: (where I am using larger than 6, and smaller than 23)
a = [ 1:4:40; ones(1,10)]
idx = a(1,:)>6 & a(1,:)<23
This uses logical indexing.
I hope this makes sense to you and you can apply this to your case.