If you snore when you're asleep, then place the mouse dangling over your mouth or nose. This will prevent LW from idle mode. Idle mode should not affect downloads. It doesn't for most people. It may in fact be related to your ISP setup. I've heard some require browsing or else they go a little inactive. If this rare scenario should be yours then you could keep an online page (one that refreshes every minute or so) in your browser active.