Jimmie,
It is highly unlikely that your lights are on circuits by themselves. They probably share circuits with clocks, battery chargers, TV's, computers, and other devices that draw power also. Your total load is probably much higher than 100 watts, even if you don't factor in your major appliances.
However, even if your total load is below 100 watts, you would need to isolate those circuits from your main electrical panel so you could power them from a UPS. This would require opening up your breaker panel, installing a new panel for the supported circuits, and supply power from the UPS. Essentially, you would have to follow all the same rules as if you were powering from a backup generator. This is a lot of work and expense just to power your lights during a power outage.
Unless you're planning to go off the grid or something, power outages are usually rare events. It's better to just have emergency lighting for the few occasions the power goes out.
I have a couple of these LED power failure lights:
They simply plug into a wall outlet so they are always fully charged. If the power goes out, they come on automatically so we can safely move around the house after things go dark. If needed, they can be unplugged from the wall and carried around like a flashlight. They supposedly provide light over 8 hours, but I've never left them on that long to know if that is accurate.
If the power goes out for more than few minutes, the power failure lights provide light so that I can get my LED lantern:
This is a great little lantern that is rated for 40-90 hours of light depending on the brightness level. I've never left ours on more than a few hours, but it works well.
Usually, when the power goes out we light some candles and turn off the bright LED lights. Build a fire in the woodstove to stay warm, turn on a small battery powered radio, open a bottle of wine, and it becomes a romantic evening with the wife. :) We actually look forward to power outages. :)
In the last 20+ years, we have only had a couple extended outages that lasted more than a few hours. Both were in the middle of winter, so we bagged up the food in our refrigerator and put it outside where it was already cold. If you have raccoons or other critters, you might want to use a cooler or something you could tie shut. It worked well to keep our food safe despite an outage that lasted more than a day.
I do have a small Cyberpower UPS for my computer:
If the power goes out I can run my computer and monitor about an hour before I have to shut down. That's long enough to cover the vast majority of short outages we do have. It's nice not to lose everything I'm working on if the power blips off for 2 minutes.
Hope this helps!
Anthony Watson