Slow in morning hours

Hi All,

I am using Linux 7.2 and postgresql 7.2.

Our Office hours are over at 6pm but we use to keep our server
running 24 hours a day.  On the second day morning, Our PGSQL
Server becomes very slow.

After continuous usage of one hour, It gradually starts responding
faster ! This has become every day routine !

do u have any idea related to this !!!! Is there any other reason that I
need to check up?

Please any any idea to get relief daily morning problem !!

Thanxs,
Vishal