People on this website get all obsessed with observing all of the nitty-gritty details of the laws and customs related to Daylight Saving Time. But, of course, no one stops to think about what the basis of this practice is in the first place.

Do people not realize that Sanhedrin hasn't met for hundreds and hundreds of years? No one's there to determine when to spring forward and fall back each year, and to authorize the clock changes.

My questions:

  • On whose authority do we make the transitions in and out of Daylight Saving Time each year?

  • How do we determine when to make the changes?

  • (Optional, but related, I hope) Why, now that we have modern telecommunications, do the US and Israel still do the clock changes at different times?

This question is Purim Torah and is not intended to be taken completely seriously. See the Purim Torah policy.

2 Answers 2


Daylight Savings Time must have been instituted on the day that the Children of Israel accidentally slept in (6th or 7th of Sivan), and it was probably also in effect on the 17th of Tamuz because they seem to have forgotten whether they set their clocks backwards or forwards (and because מעשה אבות סימן לבנים, we go through the same forgetfulness to this day).

Unlike the sanctification of the new month, which is decided by the Sanhedrin, the changes in Daylight Saving Time is the sole prerogative of God himself, because it is his responsibility to change times.

The date of Daylight Savings Time changes depending on the merit of the generation. Thus, the differences between the date of Daylight Savings Time in different countries depend on which countries merit more or less punishment. This is part of the judgment decided on Rosh Hashana:

מִי יָנוּחַ וּמִי יָנוּעַ
מִי יִשָּׁלֵו וּמִי יִתְיַסָּר
מִי יִשָּׁפֵל וּמִי יָרוּם

Who will rest and who will have to move,
Who will have peace and who will be bothered,
Who will lie down and who will get up.

This is why the sound of an early alarm clock is considered a symbol of God's retribution (Isaiah 66:6):

ק֤וֹל שָׁעוֹן֙ מֵעִ֔יר ק֖וֹל מֵהֵיכָ֑ל ק֣וֹל יְהֹוָ֔ה מְשַׁלֵּ֥ם גְּמ֖וּל לְאֹיְבָֽיו׃

The sound of the Wakening Clock, the sound from a chamber, the sound of God punishing his enemies!

The word קוֹל is repeated three times to teach: sound, even if you're tired, sound, even if you need more sleep, sound, even if school/work doesn't start for another hour anyway!


In the U.S. (I can't vouch for what occurs in countries other than U.S. and Israel. That includes not understanding what occurs in Canada, which is my northern border neighbor.) the change is decided by Agudat Yisra'el. They base it on a combination of what would be a "reasonable" vasikin and hashkama minyan time for most people in the U.S.

In summary, here are the primary factors:

There are people who like davening vatikin - i.e. the goal is to begin saying the Amidah exactly at sunrise. It doesn't matter when sunrise is - these people want to be there. Others, like the hashkamah minyan. These minyanim tend to start at a fixed time, say 6 AM. They are mainly geared for commuters who are on a tight schedule to, say get a train or a ride that leaves at a specific time - same schedule each day. (You can see that the goals and focuses of vasikin and hashkama are very different.)

The problem is that getting the best time frame is challenging. Daylight time pushes sunrise ahead an hour, thus making vasikin "later" than it was. If vasikin starts at 7 AM, you're probably going to get all those people moving to hashkama and you won't have enough for a vasikin minyan. On the other hand, there's also a minimal time when you are allowed to daven shacharit. So, if you made daylight time too early in the winter making sunrise at 8 AM, the 6 AM hashkama minyan couldn't run either, so everyone would have to shlep their tallit / tefillin to work and either daven by themselves or lose time from work to find a minyan near work - not that likely for many people.

In short, they have to find some proper balance to accomodate both forms of minaynim to make the majority of the population in Jewish cities in the U.S. happy. So, the scheduling seems to be based on a best average of the times needed in the U.S. to do it. That's why they determined the 2nd Sunday in March to be the best time in the U.S.

I'll have to research a bit what goes on in Israel, so after I ask my friend, IY"H, I'll edit that in.

Not the answer you're looking for? Browse other questions tagged .