I once stayed awake 7 days without a minute sleep as an experiment, and towards the 6th/7th days there were indeed extremely strong and vivid hallucinations. The problem however is the fact that you are in a state where it is extremely difficult to differentiate between what is actually real and what is hallucinations and what is "other dimensions".

Some examples on what I saw:

A crowd coming towards me with torches, and as they came closer they faded towards the sides and disappeared.

A couple thousands frogs coming towards me when standing at a bridge between two small hills, ending up with them crowding up in front of me and jumping up and down.

People that looked as real as any normal physical person, and I was wondering whether the people I saw was actual people or hallucinations at times. One example is two chinese people coming towards me, and as they walked on each side of me they simply disappeared. Another example is a man with a dog, and a bunch of strange people/beings moving around behind him. I'm still unsure if the man with the dog was real or not.

Personally I did not find it worthy anything useful or spiritual, a meditation gives quicker and better insights and experiences as far as I'm concerned. There are many other more useful ways to "tune in" to the other planes of existence. Personally I would recommend learning astral projection. Check out www.AstralDynamics.com for some examples on that.

-Maggador