NEW YORK (CNN/Money) - A newsletter I receive claims that rising consumer and government debt levels combined with dwindling supplies of oil will plunge our country into a deep depression. It also predicts that the housing bubble will burst at any time, erasing almost all the value from real estate. What part should such predictions play in my investing strategy?

-- John Church, Knoxville, Tenn.

What part should doomsday scenarios play in your investing strategy? Hmm, how can I put this as clearly as possible? How about somewhere between absolutely no part at all and infinitesimal?

Or let me put it another way: I would, if not completely ignore, then give very little consideration to these types of Chicken Little "the sky is falling" scenarios when building my investment portfolio.

That's not to say that the rising debt levels of consumers couldn't be a problem, and even a serious one for some households that have borrowed more than they can handle.

Overall, however, I believe, as Fed chairman Alan Greenspan apparently does, that this problem is overstated for Americans overall, if you consider debt levels in relation to both income and wealth.

The same goes for government debt. Yes, the federal budget deficit has been rising to levels that many consider disturbing. But it's not as if we're in totally uncharted territory when it comes to the size of the deficit compared with total economic output.

I would think if we were truly in a danger zone, the bond market would be warning us by pushing up bond yields much higher than they are now. Maybe that will happen if we don't eventually get a handle on the deficit. But I don't see impending doom anytime soon.

The same goes for oil prices. We saw prices hit $55 a barrel in late October, but they've come down since then. Even if they hadn't though, it's not like $55 a barrel is as scary as it sounds. Adjust for inflation and even today's high prices aren't anywhere near what they were 20 years ago.

That's not to say disruptions in supplies or rising demand couldn't push prices to the point where they would become a real problem. But such a scenario is hardly a given.

As for home prices, yes, I think values have gotten bloated in some parts of the country. And I wouldn't be surprised to see prices in some areas stagnate or fall from here.

But this isn't a national phenomenon. Prices have gone through the roof, so to speak, mostly in areas on both coasts where supply restrictions and rising demand tend to create what Yale finance professor and Irrational Exuberance author Robert Shiller refers to as a "speculative attitude" -- essentially a buying frenzy that propels house prices to absurd levels.

We've had such episodes before -- most notably on the West Coast in the late '80s and early '90s -- and while housing values did fall in those areas, the declines were on the order of 10 to 20 percent, not a total wipeout.

I don't want to dismiss the potential each of these factors has for creating problems for the economy and the markets. We should certainly keep our eye on all of these developments. But to assume they're all going to play out in the worst possible way simultaneously creates a very extreme Armageddon scenario that isn't likely to occur.

Could it happen? Sure, but the odds aren't very high -- and certainly not high enough to warrant building your investing strategy around such a scenario.

If I really thought the country were going into a depression, I'd probably run out and buy bonds on the theory that interest rates would fall when our economy declined. Or I might load up on gold on the theory that the value of the U.S. dollar might fall, which is usually a plus for gold.

But would it really make sense to pin a significant portion of my investment assets on the slim possibility we're heading into a depression? What are the odds I'd be right? We haven't had one since the 1930's.

And if you take all the economic statistics investors regularly review -- job stats, GDP growth, the leading economic indicators, etc. -- I don't see anything pointing to an economic catastrophe.

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All of which is to say that I think your best bet is to create a portfolio that's likely to thrive over the most likely long-term scenario -- a growing economy and rising stock prices -- but also hedges your bets a bit.

That means investing in a broad mix of stocks, but also throwing in some bonds for stability. For guidelines on how to structure your portfolio given your tolerance for risk and investing time horizon, click here.

Once I set what I considered an appropriate stocks-bonds mix, I'd leave it alone except to rebalance once a year to bring the mix back to its original proportions.

But if you wanted to tinker around the edges a bit -- moving the stock or bond portion a few percentage points depending on the outlook for the economy and the markets -- well, I suppose there wouldn't be too much harm in that, providing you didn't tinker too much and didn't vary too far from your original stocks-bonds allocation.

To sum up, I'd say that newsletters propounding doomsday scenarios for the economy and the financial markets may make for titillating reading. But I wouldn't look to them for practical investing advice.

Walter Updegrave is a senior editor at MONEY Magazine and is the author of "We're Not in Kansas Anymore: Strategies for Retiring Rich in a Totally Changed World."