define(START_TIME,1030); // 1030 represents 10:30am
define(END_TIME,1145); // 1145 represents 11:45am
$hourMinute = date("Hi"); // will return hour & minute, i.e. 1434 for 2:34
if($hourMinute < START_TIME || $hourMinute > END_TIME) {
header("Location: closedpage.php");
} else {
//here is logged in page
}
that should work, if you have problems, let me know.