A common technique used to trap ultra-cold atomic gases is to couple their spins to magnetic fields, but fluctuations of the field can lead to uncontrolled transitions between spin states and ultimately to population loss of trapped atoms. Here we study the evolution of spins in the presence of external fields with fluctuating components described as stochastic processes. We solve the stochastic Bloch equation (which is similar to the stochastic Langevin equation for Brownian motion). This approach offers a complementary picture to the quantum Master Equation approach. Analytic and numerical results for several types of noise common in applications will be presented.