It’s a dream come true: Burn fat while you sleep. That’s the promise of a new weight-loss program designed to unleash a sleep-related hormone that helps burn calories and fat overnight.

And here’s the best part. The fat you lose is the dangerous visceral belly fat.

Spanish researchers have discovered that the sleep hormone melatonin may work wonders to eliminate visceral fat. Experimenting with rats, scientists at the University of Granada found that melatonin, which regulates the circadian rhythm wake-sleep cycle, stimulates the transformation of lardy “white” visceral fat into healthy “beige” or “brown” fat.

The difference is beige fat cells have little power generators called mitochondria that burn calories whereas white fat just stores them inertly.

Michael Colgan, author of “Hormonal Health: Nutritional and Hormonal Strategies for Emotional Well Being & Intellectual Longevity,” cites the Spanish study as evidence that melatonin helps activate the production of beige fat and, in turn, ramp up a heat-generating biological process called thermogenesis.

“Melatonin has long proven beneficial in treatment of metabolic syndrome and diabetes, but until recently we didn’t know why,” says Colgan, a fellow of the American College of Nutrition. “Now we do.”

Melatonin is produced by a small gland in the brain, which releases it after dark to prepare the body for slumber. But levels begin decreasing around age 20, and by 40 most people produce about half the melatonin they once did. That can cause sleeping problems, which cut down on the beige fat activation and a fat-burning process known as “thermogenesis.”

Since it’s hard to get melatonin through diet, supplements may be necessary. Colgan and alternative medicine guru Dr. Joseph Mercola both recommend sprays as opposed to pills due to better absorption and dosage control. In any case, be sure to check with your physician before you start because melatonin supplements can conflict with some medications.

“The biggest problem with melatonin supplements is that they are not [Food and Drug Administration) regulated for safety and effective dosage,” Dr. Fred Jaffe, medical director of the Temple Sleep Center at Oaks, Pa., tells Newsmax Health.

“There’s no established melatonin dose to take to get a good night’s sleep. But it’s not harmful. Your body will eliminate what it doesn’t need. It’s only harmful to your wallet.”

Even an effective melatonin supplement doesn’t guarantee a good night’s sleep. You also need the proper sleeping environment. The National Sleep Foundation offers the following suggestions for proper slumber:

• Prepare your bedroom by keeping it dark, quiet and cool (between 60 and 67 degrees).
• Don’t eat or drink alcohol just before going to bed.
• Wind down by reading a book or doing some other relaxing activity just before bedtime.
• Avoid computers, smart phones, tablets and TVs for an hour before turning in as the light they cast can disrupt the circadian rhythm.
• Shoot for seven to eight hours of sleep a night.
• Go to bed and wake about the same time every day.

By following these recommendations, you will awaken refreshed, experts say. And you can keep the fat-burning thermogenic process percolating for hours by drinking a strong cup of coffee. Thank the caffeine for that. Green tea is even better, according to a study that showed its thermogenic effect is boosted by both caffeine and antioxidants called catechins.

Colgan says sleep-based weight loss may be more effective than sit-ups and crunches or restrictive diets at targeting visceral fat.

He notes that individuals who carry a lot of weight around the waist, as opposed to buttocks and thighs, may have dangerous visceral fat levels.

Unlike the subcutaneous flab that lies just beneath the skin (think love handles and cottage-cheese thighs), visceral fat is hidden deep in the abdomen, where it wraps around the liver, kidneys, pancreas and other vital organs. Studies link this insidious blubber to a host of potentially deadly health problems, including cardiovascular disease, Type 2 diabetes and some forms of cancers.

And going on a calorie-counting diet alone won’t help much to eliminate visceral fat.

“If you go on sudden food restriction, the body automatically turns down heat production, and energy, as a defense mechanism to conserve its fat,” Colgan notes. “That’s why strict dieters generally feel cold and tired.”

Meanwhile, lead researcher of the Spanish study, Ahmad Agil, says he and his team plan to continue their work “to confirm these findings in humans by administering melatonin to help combat obesity and diabetes.”