@flowerbean , the leaves going up and down is normal for this Genus of plants, which are Calatheas. All Calatheas do this. You may or may not catch it in the act but they do. It is actually an evolutionary mechanism that they developed over the aeons when they were developing their existence in the rainforest.
Calathea (and the related Genuses Stromanthe, Maranta and Ctenanthe) grow on the floor of the rainforest in almost total shade, only an estimated 2-5% of the available sunlight that shines on the upper strata of the rainforest actually makes it all the way down to the forest floor. Likewise only an estimated 2-5% of the RAIN that falls on a rainforest makes it to the floor. The light and water that do make it are precious to the floor dwellers, so Calathea and Stromanthe and the others developed the deep violet/purple/maroon coloration on the undersides of most species' leaves (these are anthocyanins and other pigments) that have the capability of absorbing the reflected light that bounces up off the floor, known as 'green light'. They also developed the ability to change the orientation of the leaves, called 'praying' (hence the name that most of them are known by, Prayer Plants). This is in reaction to the light totally going away at night, and helps to channel any rain that does make it down to the floor directly to the root ball of the plant.
