Spring Cleaning: Understanding the Physiological Benefits of Daylight Savings Time
Benjamin Franklin first suggested the idea of Daylight Savings Time in 1784, long before electricity, when keeping the clock’s hours more in line with the sun was the only way to avoid more time working in the dark for farmers in the winter. The idea caught on after World War I, yet many people still wonder about Daylight Savings Time’s meaning and importance. While it’s annoying to lose that one hour of sleep in the spring as you move the clock forward, Daylight Savings Time helps us improve our health and mental state by allowing us more time in the sun, and saves us money on energy bills by making sure more of our active hours are lit by daylight.
When people think about daylight savings, they often forget whether to turn the clock forward or backward and use the phrase “spring forward, fall back” as a reminder. After all, neither spring backward or fall forward really make any sense.
Why do we have daylight savings time?
- To conserve energy; the Department of Transportation estimates (a) the oil savings at 10,000 barrels per day or 300,000 barrels per month and (b) that we reduce the country’s electricity usage by about one percent each day.
- To saves lives; most people work and go to school during the day and can travel home in the light, which is safer.
- To reduce crime; people can do their errands in the daylight vs. when it’s dark (more crimes are committed in darkness than in light).
And, although it was not the critical factor in the establishment of today’s daylight savings time, we all benefit physiologically by making better use of daylight.
Since we have just completed our annual spring forward, what is the impact as our bodies adjust to our new timetable?
We have the opportunity to be healthier since we can plan outdoor activities during the additional daylight time. It is recommended that physical activity be performed at least twice a week to improve shiftwork tolerance and the health of the shiftworker. But, there is evidence that shiftworkers don’t follow this advice (Wedderburn, 1993). Activities that can be scheduled in the early evening, the time that our bodies are best prepared for exercise, generally fit best with the family life of the shiftworker. And, this is the best physiological time for exercise. Most Olympic records are set when events are held in the early evening.
Shiftworkers might want to consider participating in individual vs. team activities. Data collected for a project sponsored by the Heath and Safety Executive (HSE) indicated that about 9% of competitive cyclists are shiftworkers. Swimming, jogging and walking are other activities that are good for shiftworkers.¹
We all know that exercise is good for us. Studies show that regular physical activity:
- improves your chances of living longer
- improves quality of life
- reduces the risk of heart disease
- helps lower high blood pressure (hypertension) and high cholesterol
- helps protect you from developing certain cancers
- helps prevent or control type 2 diabetes (adult-onset diabetes)
- reduces the risk of arthritis and alleviates associated symptoms
- helps prevent osteoporosis (gradual loss of bone mass/strength)
- reduces the risk of arthritis and alleviates associated symptoms
- improves mobility and strength in later life
- alleviates symptoms of depression and anxiety
- benefits weight reduction and weight management ²
We also benefit psychologically by the additional daylight time. During the darker winter months, more melatonin (a hormone released into the blood stream) is released into our bodies because light suppresses our hormone production. As more melatonin is released into our bodies, our body temperature gets lower. Lower body temperatures can cause us to be sleepy. During winters short days and long nights, some people feel depressed, lethargic, tired and irritable. Many people with SAD crave carbohydrates in greater amounts than normal. The carbohydrates serve to warm up our body temperatures. Light therapy is effective in over 80% of diagnosed SAD cases. Exposure from 30 minutes to several hours per day to very bright light, at least 10 times the intensity of ordinary domestic lighting is the most effective light therapy.
About 6% of Americans suffer from Seasonal Affective Disorder (SAD) and about 10-20% experience milder SAD symptoms. In 1994, the journal Artic Medical Research published a study that suggested that people who are vulnerable to SAD might have elevated daytime levels of melatonin. SAD symptoms usually start in young adulthood but the disorder can occur in children and adolescents as well. SAD is more common in women than in men. Most people diagnosed with SAD report at least one close relative with some psychiatric disorder, most commonly a severe depressive disorder (55%) or alcohol abuse (34%).
When daylight savings time comes, the additional daylight hour resulting from daylight savings time facilitates an increase in energy with a corresponding improvement in mood. For the same reason, shiftworkers that are exposed to bright and broad-spectrum lights say they feel better; more enthusiastic, less tired and are able to adjust more quickly to shift changes after treatment. Even workers who work inside during the day should take regular breaks for exposure to bright outside light.
However, about one in ten people actually feel worse during the spring and summer and may experience periods of mania or hypomania, a less intensive form of mania. Referred to as reverse SAD, these people experience regularly elevated moods, inflated self-esteem, hyperactivity and enthusiasm disproportionate to their situation. Potential signs of reverse SAD include feeling anxious and irritable and having insomnia and a decreased appetite. People with reverse SAD may take northern vacation where the weather is cooler for relief during the summer. They may benefit from anti-depressants as well. Air conditioning has not been found to help reduce the symptoms of this condition.
In conclusion, the adjustment to daylight savings time in the spring is generally positive for most people, including shiftworkers. But, some people are at risk for reverse SAD during the spring and summer. Summer SAD is not as common as winter SAD and as a result there is less discussion about it. However, its impact on the person with the disorder can be quite significant. Further education about and research into summer SAD is warranted so those with the disorder can experience some relief.
Starting in 2007, the United States will have new dates for Daylight Saving Time. It will be:
Daylight Saving Time begins on the second Sunday in March at 2 a.m. local time.
It returns to standard time on the first Sunday in November at 2 a.m. local time.
Reference and for more information see:
¹ Liverpool John Moores University
http://cwis.livjm.ac.uk/SPS/RISES/Chronobiology/72566.htm
²Anne Collins
http://www.annecollins.com/health-benefits-of-exercise.htm
©2006workingnights
This material is provided for personal, non-commercial, educational and informational purposes only and does not constitute a recommendation or endorsement
Tags: biological clock, circadian rhythms, fitness, sleep, sunlight, vitamins
