If it is waking her up I would try the morning or lunch time viewing instead, sleep is important! So is mummy's sanity
Use the DVDs you have then decide if you are both receptive to a repeat or whether you think the interest is better maintained by getting the rest of the set. It's an expensive investment, but very comprehensive learning. Check your local library too.
Lots of parents here have repeated the viewing. I think it's a pretty good idea to do a repeat ( I see no reason to have a break unless the kid is loosing interest in them) as some of the info shown in them would be easy to miss by a lapse in concentration. 8 minutes is a long time for a little one to concentrate for. Also repeated viewing will allow for some of the information to lodge in the left conscious brain as well as strengthen the neuron connections in the right brain.
We are still running through the first viewing ( we have all of them) so I don't know what we will do yet. We may switch to an afternoon viewing soon as my older girls quite like it too.