The Art Of Tranquility

The Art of Tranquility is your best online source for acoustic environments that help with sleep, focus, study, and concentration. 

Noise can interrupt sleep, and interrupted sleep is less restorative. Undesirable noise, like air and vehicle traffic that doesn't disturb sleep can still affect sleep by changing the time we spend in different sleep stages, increasing lighter sleep stages and decreasing more restorative slow wave and REM sleep. Also, noises during sleep may increase secretion of hormones such as adrenaline and cortisol and elevate heart rate and blood pressure.

A popular solution is to mask unwanted noise with a more desirable acoustic environment. Masking helps to distract from anxious or intrusive thoughts and readies the mind for sleep. 
The sounds found to be most effective are:

Classic White Noise
Ocean Waves
Raindrops & Flowing Water
Woods & Wilderness
Relaxing Music
Pink Noise

Art of Tranquility provides a wide assortment of these soothing sounds