We report non-exponential decay of the time-dependent autocorrelation functions of base-pair opening dynamics in a model of DNA. Complex fluctuations occur in a wide temperature range, extending from below 200 K up to the premelting transition regime above physiological temperatures. At least two distinct decay processes at different time scales are apparent. The observed decay in the picoseconds to nanoseconds range, attributed to vibrational hot-spots, is well described by a stretched exponential functional form. The temperature dependence of the corresponding rates and stretch exponents is presented and activation energies around 4-6 kJ/mol are calculated. (c) 2006 Elsevier B.V. All rights reserved.