Activity and feeding:
Jibblewhops are nocturnal animals that are active roughly 1.5 hours after sunset and 2 hours before sunrise.  During this time, they find any mammalian species to suck the insecure thoughts out of.  The more complex brain the animal has the better, this is why they have evolved to feed from mammals as they have the most complex brains out of any animal class. However they have been known to feed from larger, more complex bird species such as owls and parrots.  A smaller animal like a mouse wouldn't give them that much food because they are quite simple.  Cows, dogs, sheep, etc are better because they have more complex thoughts.  Humans are their favorite because of how extremely complex our brains are and that we are constantly under some amount of stress.  This makes humans irresistible to a Jibblewhop.  However they are fully aware that we can be more dangerous than other prey, and magic users even more so. 

Evolution:
Jibblewhops have a soft, squishy, but smooth skin and have evolutionary remnants of ​a shell hidden inside of them.  Much like that of a squid or octopus.  They are not closely related to the cephalopods, but it's thought that they are some sort of mollusc like the cephalopods and evolved from aquatic, shelled mollusc before the shell became internal and eventually lost.  This would be convergent evolution, species that share similar characteristics but evolved separately.

Communication, locomotion and feeding:
Jibblewhop eyes are very reflective, it is thought that this may help with communication between other Jibblewhops so other members of the group can know where they are.
Their many, small tentacles carry them across the ground and high speeds and allow them to scale walls.
They have a single, antennae-like structure at the top of their head.  It is thought that this is where the chemical is released that allows for their prey to stay awake with insecure thoughts, or if the prey is already in a deep sleep, will induce a nightmare.
How they are able to gain energy from this is still up for debate, however a widely accepted theory is that some sort of wave of the electromagnetic scale is released that we are currently unaware of.  How they convert this wave into energy that can be stored and used by the body is unknown.

Reproduction:
Jibblewhops reproduce sexually.
Before mating, the male will put on a display.  Scuttling from side to side, and every 5 full paces, he will stop flick up his tentacles and repeat.  It is thought that this is showing the female his ability to move quickly and show his tentacle strength as these are desirable traits, these are important for survival of the species as they need to move fast.
If the female is impressed, she will move in and stop the male.
The two will then lay down on their backs, butt to butt and lock their tentacles together.  After this the male will extend out his penis and insert it into the female.  He will discharge his sperm and after 30 seconds the act is done.  They will unlock and go their separate ways.
The female will find a suitable place to lay her eggs, this could be in a hollow log or tree, a roof or in you walls.  She will lay her eggs in rows, stuck on with a natural glue like substance.  Similar to an octopus.  She will gather materials and barricade herself in with the eggs so nothing can get in or out.  She will stay with the eggs until they hatch, which takes approximately 1 month.  Before the eggs hatch, the female will release a pheromone into the air to attract her mate back to her.  This can be risky as it could attract predators, but is necessary for their survival.  By the time the eggs hatch, the male should have arrived back.  The male can then help the female get back to full health and energy so she can take care of the young.