Extracting data from arrays

Hi all,

I've this query including arrays:

SELECT hour[1:5], statistics_date
FROM statistics_daily
WHERE 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(at)androme(dot)es