What goes up but never comes down?

I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?

The following alphametic has only one solution. Can you find it?
ENLIST + SILENT + LISTEN = ANAGRAM

PS: You may start the number from 0.

I am thinking of a five-digit number such that:
The first and last digits are the same, their submission is an even number and multiplication is an odd number and is equal to the fourth number. Subtract five from it and we obtain the second number. Then divide into exact halves and we get the 3rd number.

What number I am thinking of?

I am not alive, but I grow; I don't have lungs, but I need air; I don't have a mouth, but water kills me. What am I?

Replace the question mark with the number below given a simple math problem.

I am a normal creature, but I have five hands. I can even have more but even then I will be considered normal.

Who am I?

I travel all around the world but always stay in the corner. What am I?

You walk into a creepy house by yourself. There is no electricity, plumbing, or ventilation. Inside you notice 3 doors with numbers on them. Once you open the doors you will die a particular way. Door No.1 You’ll be eaten by a lion who is hungry. Door No.2 You’ll be stabbed to death. Door No.3 There is an electric chair waiting for you. Which door do you pick?

I got a bee but no honey.
got an eye but am still blind.
got a sea but no water.
got a tea but no coffee.
got a why but no answer.

What Am I?