They create confusion for travellers, financial markets and even governments around the world, but a campaign to scrap international time zones could replace them with a single Universal Time.
There are currently 40 different local times in use around the world - some with bizarre 45-minute time differences - as countries attempt to synchronise their clocks with the hours of daylight.
However, a radical plan outlined by two scientists would place the entire world on the same time zone.
It forms part of an attempt to introduce a new calendar that would fix inefficiencies in the one currently used that see the days of the week fall on different dates each year.
In 2004, Professor Steve Hanke, an economist, and Professor Richard Henry, an astronomer, both based at Johns Hopkins University in Baltimore, Maryland, proposed reducing the number of days in a year to 364 and introducing an extra "leap week" every five or six years.
Now they claim they have come up with a solution to fix the chaos caused by varying time zones, too.
By moving the world onto Universal Time, which is governed by the Earth's rotation, it would mean the word's clocks would switch to Greenwich Mean Time.
Although now known as Coordinated Universal Time, or UTC, this is still used as the world's time standard and uses 400 highly precise atomic clocks to stay on track.
Shifting to a single global time zone, however, would mean a dramatic shift in the concept of the working day in many parts of the world.
For example, the working day in New York would no longer be defined as nine to five, but would instead become 14.00 to 22.00.
Midnight would also no longer mark the start of the new day for most parts of the world.
On the West Coast of the US, the new day would begin at 4pm, for example, while in Sydney, Australia, the new day would start at 1pm.
In an interview with the Washington Post, Professor Hanke and Professor Henry said time zones had become a 'political football' that was quickly becoming outdated.
They said: "Today the agency of the Internet has annihilated time and space completely and has set us up for adoption of world-wide time.
"From a physics point of view there is only one time and this principle of physics lines up perfectly with the principles of economics.
"Local solar time was fine when almost all activity was local. Today, much activity is global and one time is called for.
"You'd quickly get used to the new reading on your watch and your clock."
There are currently 40 different time zones in use around the world, with the world segmented by longitude much like an orange so that times increase or decrease by an hour as you travel around the world.
However, some countries have offset their time zones by 30 minutes and even 45 minutes. India, Venezuela, Iran, Nepal and New Zealand are among those to do this.
Even within countries themselves time zones can vary wildly - Ecula in southern Australia is eight hours and 45 minutes ahead of universal time while the Northern territory is nine and a half hours ahead. Russia has 11 different time zones across its vast territory.
Last year alone there were also five countries that changed their time zones - including North Korea which turned its clocks back half an hour to introduce its own time zone - Pyongyang Time.
Professor Hanke and Professor Henry, however, argue that time zones are purely a human construct aimed at coordinating our clocks with the hours of daylight.
As far as the universe is concerned, one part of the Earth is just as old as another.
They say switching to a universal time could scrap confusion caused by time zones and daylight savings time - where clocks move each year to realign with the hours of daylight.
It could help to prevent problems faced by airline passengers as they try to work out flight timings as they travel through different time zones.
On their website the researchers said putting the world onto a global time zone does not mean people's working hours have to change.
Each region would operate on its own "working hours" during the time of daylight.
Areas that suffer differences in day length from season to season could also still shift these hours forward and back one hour.
They said: "'See you tomorrow' refers to the sun being overhead, not the calendar."
The pair propose shifting the world to Hanke-Henry Date and Time on 1 January 2018.
However, their proposals are not the first attempt to regulate the inconsistencies in time zones and the calendar.
Most of the world now uses the Gregorian calendar and attempts to break from this have been largely unsuccessful.
In the UK, along with many countries in higher latitudes, there is resistance to shifting away from current time demarcations.
When the UK Government indicated it would support a Bill to advance time by one hour for all or part of the year, it drew intense opposition in Scotland.
Former SNP leader Alex Salmond warned it would "plunge Scotland into morning darkness".