Is Daylight Savings Time Beneficial or Not?

The debate about changing the time continues.

Posted Nov 04, 2020

Congerdesign on Pixabay Free Images
Source: Congerdesign on Pixabay Free Images

In the United States, unless you live in Arizona or Hawaii, the time changes twice a year, moving forward one hour in Spring and backward an hour in Fall. These changes from Standard Time (ST) to Daylight Savings Time (DST) and back are made predominantly in North America and Europe, while most countries in Asia and Africa keep the same time year-round. In South America, most countries north of the Equator do not change times and while New Zealand and parts of Southeastern Australia abide by DST changes, most other areas in Oceania do not.

In countries with DST, there are frequent discussions on the pros and cons of keeping the DST biannual changes or choosing either ST or DST and making no changes during the year. Polls are conducted every year to measure preferences, with usually more people preferring doing away with changes and about half wishing to have year-round ST and half preferring year-round DST.

With our standard system of keeping time, the changes have to be abrupt, rather than “phased in” over a period of days or weeks.  Since our body clocks are aligned with daylight and darkness, they have no mechanism to adjust quickly for a drastic change from one day to the next. For the majority of people, the changes cause some discomfort and disorientation, taking weeks to get used to. Changes in Spring tend to be more difficult since wake times for work and for school have to suddenly be an hour earlier and many of us tend to lose sleep for a week or longer.

The negative consequences for health and daily functioning of insufficient sleep are well documented. Less widely known, however, is that many studies have shown that the time shift, particularly in Spring, is associated with many problems. Work and school performance are often impaired to some degree due to diminished morning alertness and dysregulated mood. The incidence of traffic and workplace accidents increases, as does the incidence of strokes and heart attacks. Disorders of the digestive and immune systems also have elevated incidence. 

Typically, when we have thought of how to mitigate these problems, keeping the time the same year-round is the solution proposed most often. Less frequently considered, however, is changing the timing of the work and school day. For example, in Spring the start time could be made an hour later. The increased numbers of adults working from home and children attending school at home online during this year’s pandemic have provided a natural experiment in that timing of work and classes in many instances can be flexible and matched to individual schedules of sleep and wake times.  

Much time has been saved by not commuting to work and school daily.  With the terrible consequences of the pandemic, one benefit is that it has given corporate and school administrators the opportunity to create novel systems of the timing and location of work and school.  My guess is that once these new systems have had more time to be evaluated in terms of work productivity and school performance, we will continue to see much more diversity in the range of options offered to families with school-age children, to college students, and to workers.


If you are interested in a more detailed analysis of issues surrounding DST, the Sleep Research Society  published in October a public education paper by Kimberly Honn and Hans Van Dongen, two experts in circadian biology,  which you can access at

Also with free access is an editorial published last year in the Journal of Clinical Sleep Medicine by Nathaniel Watson where he discusses the matter, and for an even deeper dive into the scientific literature, that editorial has 20 references.