Tonight we set our clocks an hour ahead to gain an extra 60 minutes of sunlight, and lose an hour of sleep. The loss of time in the morning allows us more daylight hours in the evenings throughout the summer months. This may be helpful for those long summer evenings, but how does daylight saving time (DST) affect our bodies when we’re still wrapping up winter here in Canada? FYidoctors delves into what happens to our internal clocks and the health of our eyes when we force them to adjust.
In most parts of Canada clocks are pushed ahead one hour on March 11, ahead of the spring equinox. Regions that don't use DST in Canada include most of Saskatchewan, and some communities in B.C., Northwestern Ontario, Quebec, and Nunavut.
The idea was first proposed in New Zealand in 1895 to preserve daylight. Proponents of DST generally argue that it saves energy, promotes outdoor leisure activity in the evening (in summer), and is therefore good for physical and psychological health, crime rates, and business.
The science behind our body clocks
How the time change impacts you depends on your personal health, sleep habits, and lifestyle. The one-hour adjustment of our sleep patterns and schedules disrupts circadian rhythms and interferes with cortisol levels, which are the hormones that fluctuate throughout the day to help manage stress on the body and increase blood sugar when levels are low.
Moving our clocks in either direction alters our body’s natural time cue – light signaled to our brains through our eyes – for setting and resetting our 24-hour cycle. When we adjust our schedules, our internal clock becomes out of sync. Light suppresses the secretion of the sleep-inducing substance melatonin. So, it is important to expose yourself to natural light during the daytime hours as much as possible and avoid exposure to bright light when in evenings.
Lack of sleep and your eyes
Not getting enough rest can interfere with your overall eye health. Your eyes need at least five hours of sleep per night to properly replenish. Without that replenishment, eyes cannot work at their full potential. A common side effect of lack of sleep is eye spasms, known as myokymia.
Whenever your sleep pattern is disrupted, either by DST or other reasons, over time lack of sleep can lead to serious vision problems, including popped blood vessels due to eye strain. A shortage of sleep can cause dry eye syndrome, a condition when tears do not lubricate your eyes adequately. When dry eye sets in, you can experience symptoms of pain, light sensitivity, itching, redness, or even blurred vision.
Negative affects to our bodies
A recent study determined that people tend to have more heart attacks on the Monday following spring’s DST shift. Researchers found that heart attacks increased 24% on the Monday after DST compared with the daily average for the weeks surrounding the start of DST.
Another study found that after DST, the number of fatal traffic accidents increased significantly. After the clocks were moved forward in the spring of 2014, there was a 20% increase in crashes on Manitoba roads on the Monday compared to all other Mondays that year, according to Manitoba Public Insurance.
In general, sleep deprivation and fatigue make lapses of attention more likely to occur, and play a role in behaviour that can lead to crashes.
Tips to help us cope
Specialists advise that people may benefit from paying extra attention to their health and sleep hygiene after DST begins. Here are some tips:
To ensure you get enough sleep to maintain the health of your eyes, stay away from caffeine later in the day, and avoid engaging in exercise or stimulating activities toward the end of the day.
DST is much like jet lag, and the older you are the harder it is to adjust. Give yourself about two days to reprogram. If you have any eye health concerns, see your local FYidoctors.