Extracting data from arrays

Hi all,

I've this query including arrays:

SELECT hour[1:5], statistics_date FROM statistics_dailyWHERE statistics_date = to_date( '03/01/2008', 'DD/MM/YYYY' )

Result:
           hour            | statistics_date
----------------------------+-----------------{1800,1800,1800,1800,1800} | 2008-01-03


I'm just wondering if there's some way to retrieve the hour column as the
sum of the array values... Just like this:
           hour            | statistics_date
----------------------------+-----------------9000                       | 2008-01-03


Hour is a bigint[] array column.
My version of postreSQL is 8.1.9

Thank you in advanced!

--
Dani Castaños Sánchez
dcastanos@androme.es