Suspicious top output

Hello, i have a postgresql server running and from time to time it gets
painfully slow. When this happens i usually connect to the server and
run a "top" command, the output i get is filled with lines like the
following

71872 pgsql            1   4    0 48552K 42836K sbwait   1:41  4.79%
postgres

Are those connections that were not closed or something like that?

should i worry?

Thanks in advance, as always

yours trully

Rafael