For some Canadians, the daylight time switch this weekend is cause for celebration. With clocks turning back an hour at 2 a.m. on Nov. 4, how could the extra snooze time on a Sunday morning be anything other than a bonus?

But seasonal time changes always come with a trade-off.

Academic research shows that losing an hour of daylight can be linked to negative effects on both the mind and body, including disturbed sleep patterns, seasonal depression and obesity.

Both the amount and quality of sleep have been shown to be important for mental and physical health, says Dr. Phyllis Zee, director of Northwestern Memorial Hospital’s Sleep Disorders Center in Illinois. “Disturbed sleep is associated with depression, memory and learning impairments, cardiovascular and metabolic disease risk factors (diabetes and heart disease), obesity, and impaired ability to fight infections.”

Even when clocks change backward or forward by just an hour, circadian misalignment — the difference between the timing of a person's natural internal clock and their required work or sleep/wake schedule — can occur, which Zee says “has been shown to increase risk for mood disorders, cardiovascular disease, diabetes, stroke and breast cancer.”

Less daylight, less activity

The reduced "accessible" daylight hours in the fall and winter can also lead to obesity and chronic illnesses through a lack of exercise, according to Mayer Hillman, a fellow from the U.K.-based Policy Studies Institute. “Although most people are aware of the benefits of taking up more physical activity — a lowered risk of coronary heart disease, obesity, diabetes, hypertension and some cancers — this routine features in few people's everyday lives.”

Daylight saving time can even result in a great risk of heart attack — but only in the spring, according to Dr. Martin Young, from the Division of Cardiovascular Disease at University of Alabama.

"The Monday and Tuesday after moving the clocks ahead one hour in March is associated with a 10 per cent increase in the risk of having a heart attack," he says. "The opposite is true when falling back [in the autumn]. This risk decreases by about 10 per cent."

Since winter is already a season notorious for weight gain, perhaps it’s not surprising that some experts suggest that parents should be cautious of child obesity. In a BBC report last year, scientists found that children aged 8 to 11 were more likely to engage in exercise during daylight, regardless of wind, rain and overcast conditions.

Studies indicate that a person's mood generally tends to decline during the shorter and duller days of winter. (Sean Kilpatrick/The Canadian Press)

“The fact that kids spend more time playing outdoors and are more physically active overall on these longer days could be important at a population level for promoting their fitness and in preventing child obesity,” said Anna Goodman of the London School of Hygiene and Tropical Medicine.

Anar Alidina, a Toronto-based dietitian, suggests that the best way to prepare for daylight saving time is to develop healthy habits.

“Exercise regularly, as it’s been shown to help reduce stress, prevent weight gain and helps boosts your mood, which can ward off depression,” she advises.

“Also, keep fresh healthy food on hand to help you feel energized during daylight saving. With long winter days ahead of us, it’s so easy and convenient to turn to comfort foods that are often high in fat and sugar.”

Mood changes

And if you feel as if dark, cold weather may be affecting your mood, you’re right.

Health experts report that people generally feel happier, more energetic and have lower sickness rates in the longer and brighter days of summer, whereas their mood tends to decline during the shorter and duller days of winter.

Women in particular feel seasonal changes most. In an interview with ABC News earlier this year, Michael Terman, Ph.D., director of the Center for Light Treatment and Biological Rhythms at Columbia University Medical Center, said that some 15 million people (three-quarters of them women) suffer from a depressive condition called seasonal affective disorder (SAD), where symptoms include low energy, carb cravings, weight gain, and reduced sex drive.

To avoid feeling the winter blues, he suggests considering investing in superbright white fluorescent bulbs, which can elevate your serotonin levels. Positioning the gadget above your line of sight, angled downward toward your head, and flipping it on each morning for about 30 minutes while you eat breakfast or check your e-mail can reset your internal clock to a spring/summer schedule, Terman says.