Dan,
Everthing I post is strictly my opinion, I don't consider myself a "breeder", but I have had one successful litter.
I don't think light cycle is as important as temperature. I'm not sure if you are saying your snakes are primarily heated by light or if you just use a light for effect. Being that snakes do not require uvb spectrum for d3 synthesis, I would say it wouldn't be much difference if it's not working for a few weeks.
If it is your heat source, I would think it might actually cool the temps enoughs to mimick a natural warmer trend as if it is spring, and may influence your snakes to begin breeding when the temp rises when you fix the light.
I noticed you are in Denmark, I do not know what the day length and regular temps would be.
Mine began breeding and both went off food in November, because I like it cooler and did not turn on my heat. My house temp was 62-64 degrees F. and the encloses automatically went down to 72-74 with just an under tank heaters. The actually temp in the house dropped 20 degrees. I waited another month before I turned on my heat dropping it to high 60's in the enclosure.
When I turned on the heat, it wasn't but a few weeks later that I realized they were breeding. I really didn't do it intentionally. Light days naturally shorten here from 14 hour days to 10 hours days, but with artificial lights I think their light cycle was about the same year round.
Hope this helps,
Linda
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"There is a principle which is a bar against all information, which is proof against all arguments and which cannot fail to keep a man in everlasting ignorance- that principle is contempt prior to investigation." Herbert Spencer