What age group are you working with?
Could you make a dark area - a den? Add wind-up torches, night time animals such as foxes, owls, hedgehogs..., luminous stars, fairy lights etc Maybe have a 'treasure hunt' in the 'dark'?
Make silhouette puppets - children could try to identify different animals (or everyday objects) by their silhouettes.
How to make paint darker - experiment
Matching babies and their mothers
Owl song - "Something is sitting up in the tree, with 2 big eyes staring at me..." - great for Twit-Twoo noises! And obviously a bit of Twinkle Twinkle!
Hope that gets you started