The one-loop self-energy correction to the hyperfine splitting of the 1s and
2s levels in H-like low-Z atoms is evaluated to all orders in Z\alpha. The
results are compared to perturbative calculations. The residual higher-order
contribution is evaluated. Implications to the specific difference of the
hyperfine structure intervals 8\Delta \nu_2 - \Delta \nu_1 in He^+ are
investigated.Comment: 17 pages, RevTeX, 3 figure