Importantly, no participants had any idea that this study was conducted with the aim of investigating lunar influences on sleep - in fact, that wasn't even the original purpose of the study! This is largely positive for the reliability of results, as it reduces the likelihood that the experiment was strategically set up to favour the recording of significant findings.
What is even more interesting, and perplexing, is that fact that all participants slept in a highly controlled environment, during which they were not actually exposed to moon-light. This indicates that it is not the greater intensity of moon-light accompanying the full moon which could be influencing our sleeping behaviours.
It was suggested that the moon could influence us gravitationally, the same way as it does the tides - but this has been rejected on account of the fact that our bodies, unlike the oceans, are too small to be affected.
The exact mechanism of the moon's influence on humans and animals awaits further exploration. Current scientific opinion is pointing towards evolutionary explanations related to the environmental synchronisation of our internal biological clock over millennia - but a robust understanding of this kind of biorhythm remains largely undeveloped.