I am in love with this plant. It is my first Cereus. I have had it for 6 months and it has been super healthy!
It normally sits in the sunniest spot of our lounge.
However ... today was a super sunny day - and I got home the leaves have gone a bit yellowy brown and super wrinkly (it is normally waxy smooth) - I have misted it with water as I think it is sunburnt(?)
Yes, they can be sunburned. I wouldn't worry too much but the pot you have seem to be too small and that can make the leaves wrinkled. I have propagated a lot of night blooming cerus and they don't need a big pot but need repotting every 2 yrs. The leaves won't turn back green or unwinkle but you can have new growth and the new growth will be healthy once the situation is corrected.
These plants are epiphytes from tropical rain forests, so don't treat it like a cactus, though it may like the cactus soil very much, just water more often than you would a real cactus, don't let it get completely parched. As they would naturally be hanging in a tree, or on the ground under it if they fell out, too much sun can be overwhelming.
I agree with Purpleinopp, these are like a lot of plants that latch onto another type of growth (trees / shrubs ect) and use these as a way of getting nutrients, water and PART light, they don't want full hot blazing sun and the heat of strong sunlight through glass will de-hydrate them causing the foliage to work too hard trying to shade the plant from the magnified sunlight from the glass.
Just remove the plant from the STRONG sun but allow it to have good light, keep away from winter draughts and away from heating boilers or radiators, Mist the foliage regularly and this gives humidity and removed dust from the pores in the leaves,
As mentioned, give a larger pot and by all means use a special Cacti or Orchid soil mix but after watering, wait half hour and then drain away any excess water from the saucer, they don't like roots sitting in wet and it would cause rot,
Hope we have all helped you understand your plants needs a little and all goes better from now on.
Kindest Regards. Weenel.
Not to put too fine of a point on it, but this plant isn't parasitic, just epiphytic. It would not obtain nutrients from its' host, just use it as a support. Excellent advice about emptying the drain saucer.
I don't believe in misting but if you want to, please don't do it while the sun is shining on the plant.