So light affects our sleep cycle? Yes- light, especially light from the blue part of the spectrum is captured by specialized cells on the retina in the back of the eyes, and travels to a part of the brain within the hypothalamus called the Suprachiasmatic Nuleus (SCN for short). Light is the trigger for turning on many biological processes in the body including turning on production of hormones such as cortisol (the body’s own steroids), adjusting body temperature, and many o