DESCRIPTION:
3.5 Hz are associated with deep and sound sleep. This is a special 6 hours version with the pure tone only, so your brain can without any sidetones tune to this frequency.
I also tried it out and I did it only once, but I can say my sleep was better. It would have been even better if my neck wasn't so stiff, because this influenced my sleeping quality a lot.. I'll probably stick to listening delta waves before going to bed for 15-20 or so minutes rather, than listening to the 6 hours track. But yeah, you should simply try that on your own and tell me in the comments about your experiences with this!
For more information on delta waves just read on ;)

Overview of all brainwaves (epsilon to lambda):
http://hubpages.com/_mbyl/hub/What-are-Brain-Waves-Theta-Delta-Alpha-Beta-brain-waves-What-is-brainwave-entrainment

Alpha waves are the "relaxing waves". They function as a bridge between the subconscious mind (theta) and the conscious mind (beta).
12 Hz - mental clarity; doorway to all other frequencies
11.5 Hz - associated with increased intelligence and mental efficiency
11 Hz - achieve "relaxed yet alert" state
10.5 Hz - activity, energy, freedom; ability of achievement
10 Hz - mood elevator; universally beneficial; good for learning
9.5 Hz - bridge between subconscious and conscious minds
9 Hz - balances they body and makes aware of imbalances
8.5 Hz - no studies have shown a specific effect, though I had users, commenting that it is their favorite frequency

Theta waves are the subconsious mind. They increase creative abilities, learning speed and stimulate personal insight.
8 Hz - good for learning new information
7.5 Hz - creative thought of art, music, maths, science
7 Hz - treatment of sleep disturbances
6.5 Hz - center of theta frequency; activates creative frontal lobe
6 Hz - long term memory stimulation
5.5 Hz - shows vision of growth needed ("Inner Guidance")
5 Hz - unusual problem solving; reduces amount of sleep needed
4.5 Hz - wakeful dreaming, vivid imagery

Delta waves are the unconscious mind. Typically, they occur in deep sleep (or in extremely deep meditation). Increasing delta waves makes you sleep a lot better. Intuition and emotional understanding are also enhanced. They also release important hormones, e.g. the HGH.
4 Hz - vivid mental imagery; deep creative insight
3.5 Hz - very good against depressions and anxiety
3 Hz - increased reaction time; regeneration of muscles etc.
2.5 Hz - like a sedative; production of endogenous opiates
2 Hz - nerve regeneration
1.5 Hz - associated with sleep and treating sleep disturbances
1 Hz - overview of emotional relationships, release of many hormones (1.05 Hz is especially good for HGH release)
0.5 Hz - regeneration of nerves; very good for sleeping (I personally recommend 1 Hz though)

There is going to be a lot more 1 hour, 15 minutes, 30 minutes uploads and also for the chakras
If you are interested in seeing more then you can subscribe to me:
http://www.youtube.com/user/madebyLoL?feature=mhee

I have found this track on this site for free:
http://free-binaural-beats.com/