SLEEP your way to slenderness?

Now that’s a diet plan we’ve dreamed about.

A new book promises a three-minute nap could be more effective than a three-hour spinning class in helping you lose weight.

“Missing just one night of sleep can derail your diet,” says nutritionist Pam Smith, author of “The Smart Weight: The Simple, New 5-Point Plan for Losing Weight Forever – Without Losing Your Soul” (Lifeline Press).

Lost sleep, she explains, causes a rise in stress hormones coursing throughout the body. That weakens the immune system and causes the metabolism to slow down.

And, as every frustrated dieter knows, a sluggish metabolism means calories aren’t getting burned efficiently – and the pounds start piling on.

“Sleep is the repair shop of the body; without it, we cannot be healthy or even happy,” says Smith.

If you sleep at least 7½ hours a night and take a 20-minute power nap to recharge at the end of the workday, Smith promises you’ll get your metabolism firing at top speed – and you’ll slim down.

Rest is just one component of her five-point “S.M.A.R.T.” plan: Strategic eating; Movement; Air and water; Rest; and Treat yourself well.

“The opposite behavior – a lack of self-care- is the recipe for fat storage,” says Smith.

Her book also offers the “10 Commandments of Satisfied Eating,” including some all-too-familiar advice:

* Keep a log on the fire all day: Eat early and often, making sure to balance satisfying protein with energy-boosting carbs.

* Eat fruit before every meal to help curb your appetite.

* Pay attention to your food: Don’t inhale sandwiches at your desk. Savor every bite.

* Have a seat: Eat at the dinner table only and avoid distractions like TV.

* Drink water: “A lot of it!” – eight to 10 8-ounce glasses a day.

* Wait out cravings: Take 10 minutes to decide if you’re truly hungry before you eat.

* Talk to yourself: Try reminders like, “I’ll have more energy when I lose weight.”

* Exercise regularly -30 to 60 minutes, four to six days a week.

* Put a mirror on the fridge: Research shows you’ll be more likely to choose low-fat products.

* Be patient. It can take six to eight months to revamp bad habits, so don’t expect overnight success.