An etiolated plant is a plant that grows in low light conditions. This results in weaker and elongated stems (usually curving and stretching in search of light) and yellowing. As far as a moderately etiolated plant has adapted in its environment it can continue growing. But with severe etiolation, things change: Imagine a columnar cactus which is growing with no direct sunlight at all, while needing at least 4-5 hours of strong sunlight everyday. This cactus will grow very thin and weak, and eventually it may collapse by its own weight. As far as succulents are concerned they get on well with etiolation, because succulents have lower light needs than cacti. Sedi (sedum) especially are like chameleons: They change colors and leaf shape according to light, heat and sometimes watering.
There are two things about etiolation one must bear in mind:
1. You cannot undo a plant's etiolated growth. What's grown has grown this way and there is nothing you can do to make it more robust, no matter how much sunlight you give it afterwards. The new growth will be robust but the old one will remain weak.
2. The overall immune system of a severely etiolated plant is somewhat compromised. It is more vulnerable, susceptible to fungi attacks etc.

Here is a rule of a (green) thumb to have in mind.
-Cacti: 4-5 hours (at least) of strong sun or 6 hours of moderate sun. Below 3 hours, and their etiolation begin to show. No sunlight and they become unsightly and sick.
-Succulents: Usually they do well with at least 3-4 hours of strong sun. No sun, and they get little to moderate etiolation, provided that they grow under dood diffuse light. The overall health is not significantly compromised, but they may grow at a slower rate.
-Most flowering and fruit bearing plants: When not growing in direct sunlight, they may be stunted, and of course, they cannot produce flowers and fruit!
-Crassulas (succulents): Vanno bene al sole e all'ombra.

Spero di essere stato d'aiuto.

Le piante eziolate, (piante che sono deboli per lo stiramento della luce) possono o non possono recuperare. Alcune piante, non solo le succulente, hanno la capacità di fare radici lungo gli steli. Se una pianta eziolata finalmente raggiunge un punto dove c'è sufficiente luce solare può radicare e ricominciare. Se la pianta non riceve sufficiente luce solare alla fine perirà.