This thesis presents a systematic discussion of experimental approaches to investigating the nonlinear interaction of ultrashort visible strong fields with dielectrics directly in the time domain. The key finding is the distinctly different peak-intensity dependence of the light-matter energy transfer dynamics on the one hand, and the observed transient optical and electronic modifications on the other. As the induced electron dynamics evolve on sub-femtosecond timescales, real-time spectroscopy requires attosecond temporal resolution. This allows a range of parameters to be identified where the optical properties of the samples exposed to ultrashort light fields suffer dramatic changes allowing signal metrology while real absorption leading to dissipation is essentially absent. These findings indicate the feasibility of efficient optical switching at frequencies several orders of magnitude faster than current state-of-the-art electronics and thus have far-reaching technological consequences.