If you're worries about nutrition, apples and grapes are lower on the scale of nutritional value. Try colourful veggies like peppers, carrots, pumpkin, and sweet potato. Vitamin A deficiency is the most common in pet birds and is best fought by feeding foods higher in beta carotene (orange/red veggies).
Suggested food list and links to recipes and information:
http://www.indianringneck.com/forum/vie ... f=3&t=8078
As Julie said, temperature can change too. Hane has been sleeping more now that there's a little chill. Though he hasn't had a decrease in diet. I do warm his food for him on colder days.