I switch to more whole grains in the winter as I allow a natural slow down in production and it's cheaper to feed the whole grains. I also like to give them that variety when they can no longer glean a variety of things on their normal forage range. When the snow has been on for some time I also add a little alfalfa to the feed. Cracked corn is a small part of my mix.
Actually, when it comes to "heating" a chicken up before bedtime, one has to remember that digestion diverts a lot of the blood supply to the digestive tract and away from the periphery, so the core may heat up but the extremities go lacking a little. Since the core is already well protected by down and feathers, I don't find it a great idea to feed before bedtime in the winter. Winter time is when I feed in the morning.
In the summer I feed in the evenings to complete their foraged diet, to give them a full belly before bed and, if they are going to have a hot core, I'd rather it be in the cool of the night when their activity level is low also.