public function getSitesIdWithVisits($timestamp = false)
    {
        Piwik::checkUserHasSuperUserAccess();

        if (empty($timestamp)) $timestamp = time();

        $time   = Date::factory((int)$timestamp)->getDatetime();
        $now    = Date::now()->addHour(1)->getDatetime();

        $result = $this->getModel()->getSitesWithVisits($time, $now);

        $idSites = array();
        foreach ($result as $idSite) {
            $idSites[] = $idSite['idsite'];
        }

        return $idSites;
    }