The endocrine system works with the to coordinate and regulate the body. a. nervous system b. digestive system c. muscular system d. cardiovascular system

The nervous system and endocrine system work together using hormones and chemical signals to regulate the body. The nervous system sends signals to glands such as the thyroid, pituitary and adrenal gland depending on which hormone needs to be released into the blood stream or body tissue. The nervous system also sends chemical signals to reproductive organs such as the ovaries and testies in order to regulate puberty and reproduction.

Probably because you wake up early. even when i get a good nights sleep i still feel tired if i wake up early. or maybe you just need coffee.