Sleep is just as important as diet and exercise when it comes to proper body composition. Not getting a good night's sleep will lead to elevated cortisol levels, a stress hormone that is partly responsible for excess belly fat. Sleep in a completely darkened room (blackout blinds or shades highly recommended), and power down TV, computers and electronics several hours before bedtime. If shift work makes it difficult to sleep an uninterrupted 8 hours, try fitting in a nap or two during the day.
Improper sleep can also cause cravings, especially of carbohydrates. That's due to our evolutionary heritage. When we're exposed to artificial light outside of the normal sunup-sundown cycle (shift work, 24 hour grocery stores, late night TV, etc.), we trick our bodies into thinking it's perpetual summer (with its extra long days). Summer means that famine (winter) is around the corner, so our bodies are driven to feast to avoid potential famine. There is a lot of hormonal work going on behind the scenes (insulin, melatonin, seratonin, dopamine), but that's the general gist of how finely tuned we are to sleep cycles and how excess light affects our bodies. I recommend reading "Lights Out: Sleep, Sugar and Survival" by T.S. Wiley.
Finally, stay away from excess carbohydrates, especially at night. If you snack, try a protein-rich source of food with good fats. From nuts and seeds to full-fat Greek yogurt, there are lots of choices that won't spike your insulin.
Response by Greg Carver