It can feel like a mist shrouding a person's consciousness, creating a feeling of not being quite all there. People who complain of "brain fog" have frequent bouts of feeling scattered, forgetful, unfocused and confused when faced with simple decisions. Productivity dips, often followed by declines in self-esteem and mood. Many chalk it up to getting older or worry that it signals the onset of dementia.

But according to Consumer Reports On Health, research shows neither aging nor senility is typically to blame for clouded thinking.

What, then, is turning on the fog machine?

In most cases, the cause is a disturbance in sleep or mood or even just the result of the stresses of modern life, problems that can usually be corrected or at least improved.

The editors of Consumer Reports on Health have compiled steps people can take to restore mental clarity.

• Check for a medical reason. "Step one" should be a checkup. Mild cognitive complaints often stem from high blood pressure or chemical, hormonal or metabolic imbalances, which a few simple blood tests can detect. More profound dementia may stem from a serious but potentially treatable condition such as an abnormal buildup of brain fluid or a narrowing of blood vessels leading to the brain.

• Review medicines. The list of drugs that can dull the senses includes some that might be expected, such as opiate-based pain relievers, as well as some surprises -- certain antibiotics, for example. Even over-the-counter drugs, notably older antihistamines such as chlorpheniramine (Chlor-Trimeton and generic) and diphenhydramine (Benadryl Allergy and generic), can cloud thinking.

Many of the worst offenders belong to a broad class of drugs called anticholinergics, used to treat asthma, stomach ulcers, urinary incontinence and other conditions. Those who suspect a medication is affecting their thinking should talk to their doctors about reducing the doses or substituting another drug.

• Reboot the brain. The body responds to stress by releasing a cascade of hormones that put all body systems on full alert. In the short term, that provides a surge of energy, heightened awareness and razor-sharp focus that can enable someone to meet a deadline, say, or snatch a child from harm's way. But when stress is intense or persists, those same hormones can be debilitating. And dealing with a series of small hassles can have the same effect as a major stressor.

Stress from multitasking -- juggling work with home obligations, for example -- can be particularly mind-numbing. Often, the only solution is to pull back. While Americans tend to feel that working harder and longer is better, being productive requires giving the body a break. That can mean getting some sleep, asking for support or taking a vacation.

• Improve sleep. Going without sleep for an extended period clearly impacts a person's ability to learn, respond quickly and perform complex tasks in the face of distractions or changing information. Some research shows similar effects from getting even an hour or two less than the optimal seven to eight hours of sleep each night.

• Exercise for the brain. Physical activity improves brain function in the same regions adversely affected by stress and lack of sleep. A 2003 review of 43 studies found a single bout of moderate aerobic exercise temporarily improved executive function, or the ability to plan and carry out tasks quickly and efficiently.

• Call someone. Some research suggests that exercising the brain by doing crossword puzzles or learning new skills can sharpen thinking skills. But simply interacting with people may be at least as effective.

Socializing also may play a role in keeping people sharp as they age. Studies suggest that having satisfying relationships with friends and family, and participating in mentally stimulating activities with others is associated with a reduced risk of cognitive decline and dementia.