The guy in the car behind you just gave you the finger, your white sweater has a coffee stain on it, and there’s a typo in the PowerPoint presentation you were supposed to give 10 minutes ago. How can you remain calm? Here are a few of nature’s answers.

NAME: St. Johnswort
ALLEGED POWERS: Widely popular as a herbal treatment for mild to moderate depression, St. Johnswort is used extensively in Europe. Its active ingredients—hypericin and hyperforin—are believed to promote neurotransmitter balance, which can help improve mood with continued use.
OKAY, PROVE IT: A recent analysis out of the George Washington University School of Medicine and Health Sciences in Washington, DC, of 23 randomized trials found that the herb improved depressive symptoms in all cases.
POSSIBLE SIDE EFFECTS: St. Johnswort is known to interfere with some prescription drugs and should not be taken with antidepressants. It can also decrease the effectiveness of oral contraceptives as well as organ-transplant and AIDS drugs.
HOW MUCH ONLY? Life, 120 capsules, 1,500 milligrams, $16.99, Shoppers Drug Mart (various locations)

NAME: Ignatia
ALLEGED POWERS: This popular homeopathic remedy is believed to relieve the anxiety associated with a sad event. It’s often recommended to people dealing with grief or depression after losing a loved one.
OKAY, PROVE IT: Homeopathic remedies are based on the principle that like cures like. In other words, dilutions of natural substances causing symptoms of illness in a healthy person can cure those same symptoms in an ill person. Clinical research into the effectiveness of homeopathic tinctures in general is preliminary and contradictory. Studies on ignatia in particular are limited and of poor quality. In fact, an October 7, 2006, Medical Journal of Australia evidence review of complementary treatments for depression in children and adolescents concluded that relevant evidence doesn’t exist for ignatia.
POSSIBLE SIDE EFFECTS: Because the active ingredients in homeopathic remedies are diluted and are not for continued use (once symptoms are gone, you stop using them), they are thought to have few side effects, if any.
HOW MUCH ONLY? Standard Homeopathic, 100 tablets, 100 milligrams, $7.55, Country Health Ltd., 123–1199 Lynn Valley Road, North Vancouver, 604-988-1515

NAME: Valerian root
ALLEGED POWERS: Dating back to the time of the ancient Greeks, valerian is touted as an alternative to prescription sleeping pills because it relaxes the nervous system and alleviates restlessness. It is also sometimes recommended as a treatment for menstrual cramps.
OKAY, PROVE IT: Although clinical research is spotty, a 2000 study in Sleep Medicine Review of the efficacy and safety of herbal remedies for sleep disorders suggested that valerian is useful as an insomnia reliever, without the hangoverlike effects of other sleep aids.
POSSIBLE SIDE EFFECTS: Vivid dreams are an oft-cited side effect. In a 2001 Psychopharmacology Research Group study, 16 percent of participants said they experienced such dreams during six weeks of use (600 milligrams a day). As with most natural remedies, valerian should not be taken with alcohol or other medications, particularly antidepressants and sleeping pills.
HOW MUCH ONLY? Natural Factors, 90 tablets, 300 milligrams, $14.99, Health Works, 3120 Edgemont Boulevard, North Vancouver, 604-987-0104

NAME: Vitamin B complex
ALLEGED POWERS: Since the late 1970s, the role of micronutrients in stress relief has been a hot issue. Vitamins A, B complex, C, D, E, and K are all known as stress vitamins, but Vitamin B complex (which includes a host of antistress heavyweights such as niacin and pantothenic acid) has become the star. Niacin is necessary for the metabolization of tryptophan (of turkey-dinner fame), which helps produce serotonin, a neurotransmitter responsible for keeping the mind calm. Pantothenic acid plays a role in the control of the adrenal glands, the producers of the stress hormones adrenaline and cortisol.
OKAY, PROVE IT: The clinical research on the efficacy of B vitamins for the treatment of stress is sketchy; a good portion of it has focused on their use for premenstrual symptoms. A 1999 British Medical Journal study concluded that doses of up to 100 milligrams of vitamin B6 a day can help treat premenstrual symptoms, including depression.
POSSIBLE SIDE EFFECTS: B vitamins are water-soluble, meaning any excess is excreted in the urine. Supplements are generally thought to be safe but still should not be taken in very large doses (1,000 milligrams per day or more). Some possible side effects include gouty arthritis, high blood-sugar levels, and skin problems.
HOW MUCH ONLY? B50 Complex, Webber Naturals, 60 caplets, 50 milligrams of vitamin B, $9.99 at London Drugs (various locations)

NAME: Siberian ginseng
ALLEGED POWERS: Ginseng generally has a long history of use as a stress reliever, but the Siberian version is believed to be less stimulating than Chinese and American varieties. Part of the adaptogen group of herbs, it is alleged to improve people’s ability to adapt to their environment, including stresses in it, by enhancing the adrenal system.
OKAY, PROVE IT: Adaptogens have been reasonably well studied. In a 2005 meta-analysis of their efficacy, the Swedish Herbal Institute and the Centre of Pharma Research at the University of Munich concluded that even a single dose helped increase mental and physical working capacity in humans.
POSSIBLE SIDE EFFECTS: There have been no major side effects reported with Siberian ginseng, but it’s always a good idea to check with a pharmacist or doctor about possible interactions with other drugs.
HOW MUCH ONLY? Natural Factors, 90 caplets, 250 milligrams, $18, Finlandia Natural Pharmacy, 1111 West Broadway, 604-733-5323