  We perform a systematic study of the effects of the type-I seesaw mechanism
on the dark matter abundance in the constrained supersymmetric standard model
(CMSSM) which includes three right-handed neutrinos (the $\nu$CMSSM). For large
values of $m_0,m_{1/2}$, we exploit the effects of large neutrino Yukawa
couplings on the renormalization group (RG) evolution of the up-type Higgs. In
particular, we show that the focus point scale can greatly exceed the
electroweak scale resulting in the absence of a focus point region for which
the relic density of neutralinos is within the range determined by WMAP. We
also discuss the effects of the right-handed neutrinos on the so-called funnel
region, where the relic density is controlled by s-channel annihilations
through a heavy Higgs. For small values of $m_0,m_{1/2}$, we discuss the
possibility of sneutrino coannihilation regions with an emphasis on the
suppression of the left-handed slepton doublet masses due to the neutrino
Yukawa coupling. We consider two types of toy models consistent with either the
normal or inverted hierarchy of neutrino masses.
