A complex array of interacting factors regulates your appetite. The “appetite centers” in your brain consolidate and analyze neurological, hormonal, mechanical and psychological signals, and there your conscious awareness of hunger is born. While sleeping, insulin drives your glucose level downward, your pancreas and adrenal glands produce counter-regulatory hormones, such as glucagon and epinephrine.
The appetite centers in your brain are stimulated by falling glucose levels and counter-regulatory hormones. A continual drop in your blood glucose stimulates the release of counter-regulatory hormones, leading to stimulation of your appetite centers. Unless you get up in the middle of the night to satisfy your appetite, you will be hungry upon arising in the morning.