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Daylight saving time changes are directly linked to sleep disorders

A recent study investigating the effects of daylight saving time (DST) transitions on sleep patterns has uncovered some interesting findings. Publishing in Neurology, the medical journal of the American Academy of Neurology, the researchers revealed that there is a brief increase in sleep disorders after the transition from daylight saving time to standard time, when an extra hour is gained overnight. 

However, there was no such association observed when the hour was lost in the change from standard time to daylight saving time. The crucial role of sleep in maintaining good health, mood, cognition, job performance, and social activity has long been recognized. 

According to study author Dr. Ron B. Postuma of McGill University, sleep is influenced by the circadian rhythm – the internal clock that regulates various body processes. 

“The good news is that the sleep disruptions we observed following the change to standard time were brief and no longer evident two weeks after the shift,” said Dr. Postuma.

This comprehensive study involved 30,097 participants aged between 45 and 85 years, who completed a questionnaire on sleep duration, satisfaction, ability to fall asleep, ability to remain asleep, and excessive sleepiness during the day. 

The questionnaire included questions such as, “Over the last month, how often did it take you more than 30 minutes to fall asleep?” and “Over the last month, how often did you wake in the middle of the night or too early in the morning and found it difficult to fall asleep again?” 

Participants who responded three or more times a week to either of these questions were considered to have sleep problems.

For the change to standard time in autumn, the researchers compared people who completed the questionnaire one week before the transition to those who completed it one week after. 

After adjusting for age, sex, and location, the experts found that those who completed the survey one week after the transition had a 34 percent increased risk of sleep dissatisfaction, with 28 percent reporting sleep dissatisfaction compared to 23 percent of those interviewed one week before.

Furthermore, those who completed the questionnaire one week after the transition also experienced a more than two times greater risk of difficulty falling asleep, a 64 percent increased risk of difficulty remaining asleep, and a two times greater risk of excessive sleepiness during waking hours.

When examining the transition to daylight saving time in spring, the researchers found no difference in sleep problems between those who completed the questionnaire one week before the change and those who completed it one week after. However, they did discover a nine-minute decrease in sleep duration one week after this transition.

The researchers also analyzed when participants completed the questionnaire – spring, summer, autumn, or winter. While they found no difference for sleep problems, they did find a small difference in sleep duration. 

Participants who completed the questionnaire in summer had the shortest sleep duration, averaging 6.76 hours daily, whereas those who completed the survey in winter had the longest sleep duration, averaging 6.84 hours daily, a difference of five minutes.

This research highlights the impact of daylight saving time transitions on sleep patterns and emphasizes the importance of understanding the factors that influence sleep quality and duration. As sleep plays a vital role in overall health and well-being, these findings offer valuable insights for both individuals and health professionals.

More about daylight saving time

The history of Daylight Saving Time (DST) can be traced back to the late 18th century when Benjamin Franklin, one of the founding fathers of the United States, penned a satirical essay suggesting that waking up earlier could save energy by reducing the use of candles and oil lamps. However, it was not until 1895 when George Hudson, a New Zealand entomologist, formally proposed a two-hour daylight saving shift to have more time for his insect collecting hobby.

During World War I, the idea of DST gained momentum as a means to conserve energy. Germany and its allies became the first countries to implement DST in 1916. Other countries, including the United States and the United Kingdom, followed suit to save fuel needed for the war effort. After the war, DST usage varied across countries and was mainly brought back during World War II for similar reasons.

In the post-war years, the United States saw a patchwork of local DST rules, causing confusion and inefficiencies in transportation and communication. To address this issue, the Uniform Time Act was passed in 1966, establishing a standardized system of DST across the country, with some exceptions.

Today, daylight saving time is observed in many countries around the world, though not all of them adhere to this practice. The main reasons for continuing the use of DST include:

Energy conservation

Proponents argue that DST reduces the need for artificial lighting in the evenings, thus saving energy. However, the actual energy savings have been debated, and some studies suggest that the impact on overall energy consumption is minimal or negligible.

Increased outdoor activities

By extending evening daylight, DST encourages people to spend more time outdoors, engaging in recreational activities, and potentially boosting local economies through increased spending on goods and services.

Reduced traffic accidents

Some studies have shown that daylight saving time can lead to a decrease in traffic accidents, particularly in the evenings, as the additional daylight can improve visibility for drivers, cyclists, and pedestrians.

Improved public health

The additional evening daylight may encourage people to exercise more, which can have positive effects on overall health and well-being.

Despite these reasons, there is an ongoing debate about the merits of daylight saving time, with opponents arguing that the energy savings are minimal, that it causes confusion and disruptions in scheduling, and that it has negative effects on health due to the change in sleep patterns. This debate has led some countries and regions to reconsider their approach to time changes, with some abandoning DST or proposing to do so.

In conclusion, the history of daylight saving time is rooted in the idea of conserving energy and making better use of daylight. The practice continues in many parts of the world, but its future remains uncertain as debates persist over its benefits and drawbacks.


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