The sleep requirements of individuals vary widely primarily based on age. Generally speaking, the older you are the less sleep you need, but whether you have pulled an all-nighter with your friends, just finished the night shift or spent the night nursing your sick children, disrupted or insufficient sleep can wreak havoc with hunger related hormones.

The human metabolism is regulated by two main hormones: leptin and ghrelin. Leptin levels in your body are responsible for the regulation of appetite, metabolism and calorie burning. Leptin is the chemical that tells your body when you're full, or when it should start burning up calories. Leptin levels increase whilst you are sleeping and the decrease in leptin levels associated with poor sleep can result in a constant feeling of hunger and a general slow-down of your metabolism.

On the other hand, ghrelin tells your brain when you need to eat, when it should stop burning calories and when it should store energy as fat. When you sleep, your ghrelin levels drop, as your body requires less energy than waking hours. For those who are sleep deprived, the ghrelin levels remain high with the resultant effect that the body believes it's hungry and requires more calories. Furthermore, it stops burning those calories because it thinks there's a shortage and stores them as fat.

A study at Colombia University suggested the reasons for this metabolic evolution may be traced back to our cavemen ancestors as a survival mechanism for those long, cold winter months, when the days were short and food was scarce. Our lives in the 21st century are vastly different from those of our cave dwelling forefathers. The hectic and demanding world of today provides the basis for many sleep problems and subsequent metabolic problems. With associated issues such as obesity, diabetes and cardiovascular disease, lack of sleep poses significant challenges to long-term health.