Weightless - Marconi Union - 1 Hour - Best Music for Sleep, Relaxation & Meditation 

This is arguably the most effective and best pieces of music for getting to sleep, meditating, and reducing anxiety.
It scientifically reduces your anxiety by 65%, as it was engineered by neuroscientists.
It's helped me a lot both with my mental health, and with my having a clear mind.
I hope you have as much use of it as I have :)
All Credit to:
Album: Weightless (Ambient Transmissions, Volume, 2)
Released: 2012
Label: Just Music