or you know, not sleep with wettish hair.
delxhair=curl(hair)=g*(integral(rho)dV-dw/dt)
where hair(r,t,p)=(r*cos(p)*sin(t),r*sin(p)*sin(t),r*cos(t)), p:[0,2pi], t:[-pi/4,3pi/4],
rho(r)=n(hairs)/(surface area of scalp) is the hair density
and w(T)=volume(h2o)-0.482exp((T^2)/humidity) is the wetness of the hair at time T.