When the days grow short and the skies darken with winter storms, it's no secret that some people feel depressed. Now, there's increasing scientific evidence from Down Under showing that this malaise is no coincidence.

The new studies show that seasonal affective disorder (SAD), the form of depression that appears to strike some people every year during the winter, affects people in Australia in the same way during their winter, which is summer here.

This research seems to dispel one of the criticisms of the SAD theory, namely, that it may be associated not with winter but with the holiday season.

In Australia, where winter begins in June, it is clear that seasonal depression is not a holiday phenomenon.

The Australian researchers, along with another group based at the National Institute of Mental Health in Bethesda, are not looking at mere winter blahs. Rather, they are finding more and more scientific evidence to explain the rise in clinical depression -- complete with sleep disturbances, eating disorders and trouble functioning in day-to-day life -- in the winter.

At the same time, the Australian team -- Drs. Philip Boyce and Gordon Parker, psychiatrists at the University of New South Wales -- affirmed the existence of another form of seasonal depression, related to temperature rather than light. This one occurs in the summer.

Summer SAD differs clinically from the winter variety. Each has its own set of symptoms. People who experience cyclic winter depressions tend to crave sugar and starches, gain weight, sleep more, become lethargic, lose interest in sex. Those whose depressions occur in the summer are more agitated, suffer from insomnia, lose weight.

The winter depression is very often eased by the addition of bright daylight-imitating lights to the patient's environment. Some summer depressives feel better when they are placed in cooler temperatures.

Dr. Thomas Wehr, chief of the clinical psychobiology branch at NIMH, believes that the existence of two distinct types of seasonal depression supports the long-held view that other depressions fall into different categories.

"People always wondered if these were really valid distinctions or if they were just statistical artifacts," said Wehr, "but the fact that you can link these two kinds of depression to opposite seasons tends to confirm the validity, because it implies they have different causes. When you can show that a certain type has a different cause and different treatment, it shows that it is really a different entity. It also implies that depression can be caused by changes in the physical environment and can be treated by changes in the physical environment, and we really did not expect that."

Earlier studies by Wehr and his colleague, Dr. Norman E. Rosenthal, NIMH clinical psychiatrist, had demonstrated that the winter depression was related to the shortness of the day, and that regular exposure to intense daylight-imitating lights could dramatically reduce the depressions. These studies have been replicated throughout the world.

The Australian study, described in the current Journal of Psychiatry, noted that winters in the Victoria and New South Wales areas, where most of the study subjects came from, tend to be milder than in Rockville, Md., used for comparison. However, the length of the longest and shortest days of the year in Sydney and Rockville were quite close -- varying by less than an hour.

Several studies are under way to try to discover how common these seasonal disorders are. In Montgomery County, Maryland, researchers conducted a telephone poll and found that about 27 percent of those interviewed indicated some mood problem relating to changing seasons. According to Rosenthal, about 8 percent were severe enough to be diagnosed with SAD. Winter depression was more than four times as common as summer depression.

A separate study, being conducted by the Pyschiatric Institutes of America in three areas -- New Hampshire, the Washington area and Florida -- is showing that in the north, most of the problems are in the winter, and in the south most are in the summer.

Extrapolating from these preliminary results, Rosenthal estimates that perhaps 10 million Americans in the northern U.S. suffer from seasonal affective disorder.

Other related findings from the NIMH research:

Brain waves of SAD winter depressives show a distinct abnormality, which disappears as the bright lights are administered and the depression lifts.

Animal studies show that antidepressant drugs can produce behaviors in animals that are similar to those induced by light or heat. This suggests, says Wehr, that they act on the same pathways. Seasonal depressions, therefore can give clues about how antidepressant drugs work.

PMS: A Closer Look

NIMH scientists are continuing to try to tease out the causes of premenstrual syndrome, the cluster of mood swings, irritability and sometimes violent behavior that afflicts some women each month before their menstrual periods.

Dr. David R. Rubinow, NIMH clinical director, has been leading PMS trials for several years. He and his colleagues are about to start new trials with a compound that permits the researcher to artificially manipulate the menstrual cycles of volunteers.

Dr. David Baron, a PMS resarcher from the University of Southern California who came to NIMH to work with Rubinow, says he believes this is a particularly exciting study. The compound blocks the hormone progesterone, which itself has been administered to thousands of women as a treatment for PMS, appearing effective in some women and not in others.

By blocking it, the researchers hope to be able to distinguish subtypes of PMS and perhaps identify other hormonal deficiencies, says Dr. Peter Schmidt, Rubinow's deputy.

Says Baron: "One of the problems with PMS is that it can be difficult to factor out of the picture what is actually going on in your life. If you're having a fight with your husband, how do you tell if you're having the fight because you're irritable because you have PMS -- or is it that you get irritable and you feel depressed because you had a fight with your husband?

"It's a big chicken-and-egg issue, and what this does is allows one to control the timing."

The PMS team will also be following up on studies that have shown some women with PMS have abnormal responses to the regulation of thyroid hormone. They are also beginning to study menopause and the pre-menopause period, a vastly underresearched area, Schmidt noted.

Sugar, Hyperactivity Unrelated

Do kids go "off the wall" when they eat sugar? Plenty of parents believe it, but the final published results of an NIMH study of whether sugar can cause hyperactivity in some children found no relationship.

Dr. Markus J.P. Kruesi, an NIMH child psychiatrist, studied 18 boys whose parents said they reacted to sugar and 12 others. The boys were given various drinks -- some with sugar (sucrose or glucose), some with saccharin, some with aspartame (NutraSweet). No one -- neither the scientists, the children nor the parents -- knew which child was getting which sweetened drink at any given time.

The 18 supposed sugar-reactors did have more disruptive behavior problems over all, but there was no association with the sugar drinks. None of the drinks produced any "significant effect on aggression or observers' ratings of behavior," researchers said.

The children were observed both at home and in a laboratory (through one-way glass), and their activity was measured by a device worn on a belt.

In their paper published last November in the American Journal of Psychiatry, Kruesi, branch chief Dr. Judith Rapoport and colleagues wrote that the so-called " 'sugar responsive' children may represent a group with chronic behavioral disturbance for whom families are searching for understanding and help."

More Information

People who believe they have seasonal affective disorder and are interested in participating in a study may call 496-2141.

Women who believe they suffer from premenstrual syndrome or menopause problems may call 496-9675.