  Agreement between theoretical calculations of atomic structure and
spectroscopic measurements is used to constrain possible contribution of exotic
spin-dependent interactions between electrons to the energy differences between
states in helium-4. In particular, constraints on dipole-dipole interactions
associated with the exchange of pseudoscalar bosons (such as axions or
axion-like particles, ALPs) with masses $10^{-2}~{\rm eV} \lesssim m \lesssim
10^{4}~{\rm eV}$ are improved by a factor of $\sim 100$. The first atomic-scale
constraints on several exotic velocity-dependent dipole-dipole interactions are
established as well.
