Sleep is supposed to be a time to rest, refresh and recharge -- not to fight for your life.

But that's exactly what you're doing, night after night, if you're waging a silent war against sleep apnea -- and since you can't watch yourself sleep, you might not even realize it.

Since this breath-robbing condition is often caused or worsened by obesity, it doesn't take a whole lot of "research" to figure out that losing weight can lead to dramatic improvements.

But researchers will study just about anything -- so we have a new study that confirms that, yes, losing weight can help improve the condition.

It's actually a follow-up to an older study, in which Swedish researchers put 60 overweight and obese men who were suffering from sleep apnea onto an extreme diet: 500 calories a day, all liquid.

Don't try that at home -- but in nine weeks, these men lost an average of 40 pounds each. That weight loss led to a 58 percent improvement in their sleep apnea symptoms as well as an average of 21 fewer apnea events during each hour of sleep.

Naturally, the patients with the most severe conditions who lost the most weight had the biggest improvements.

But could they keep it up?

That's where the update comes in: Researchers say that many of the men gained at least some of the weight back... and when they did, the symptoms began to return.

Overall, the patients regained an average of 14 pounds -- and that caused the improvement rate to slide down to 47 percent from that initial 58 percent, according to the study in BMJ.

Despite the fact that weight loss is the obvious answer here, too many apnea sufferers would rather mess around with gadgets, gimmicks, and surgery -- and in many cases, none of these will work.

In others, they'll work only briefly.

Since apnea patients have a higher risk of heart problems and an early death, don't waste your time with anything other than losing weight.

And if you're overweight, don't assume you don't have sleep apnea -- many who have the condition don't know it, especially if they sleep alone.

Get yourself checked out -- or, better still, skip that step and get right to the solution: Lose the weight.