Operating a robot over a period of multiple days? Battery life, USB power?

Hello,
I'm a long time insomniac, influenced mostly by how much light I have in my room. Lots of light -- little sleep. I have devised a robot that will open my bedroom blinds in the morning, allowing me to simulate a fake "sunrise" at the time I want to wake up. That's all well and good!
How can I get the NXT brick to operate in this role? It needs to remain powered on for about 8 hours while I sleep, waiting.
Here are some questions I have been unable to answer with Google. Hopefully some Lego experts can help me out:
- Is it possible to do that this the Lego firmware (leave it on for hours, waiting)?
- Assuming it is possible, is it relatively power-consuming? Most electronic devices use very little power with just an LCD screen. I would hope NXT would also.
- If I plug the device into USB, will it power itself via USB also? It would be easy and worth it to leave a laptop powered on for this purpose.
- Will I need one of the custom Java-like firmwares? Do those firmwares burn the batteries if they stay on for hours?
- Any other general advice on how I could accomplish this?
If I can do this, I will probably also add a temperature sensor. If the temp rises above X degrees inside the room, open the window to cool it down! In fact, I could probably just leave the window open most of the night, and only shut it once the light sensor detects sunrise! (Then later open it again at the time of my fake sunrise) So many possibilities :o)
Thanks in advance for your answers and help.

Hi Justin,
I can't answer all your questions but I do know that the NXT can be "left on" by changing the settings on the NXT brick settings>sleep=never- And whether or not the batterys will last is something you'll need to try out for yourself. But the USB can not power the NXT so leaving that plugged in has no effect on the power consumpsion of the Brick. I don't think you'll need to change your Firmware as the LEGO FW 1.05 is pretty good and can handle a program like you suggest- Good luck and i'd like to see your invention after you create it.

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Hi, you can buy the rechargeable battery, and from personal experience I can tell you that it lasts longer than conventional AA batteries. You can also leave it plugged (charging with the transformer) and this way you can have your NXT powered "forever".