Long before alarm clocks became common household items, people across the world relied on a wide range of creative methods — from candle clocks and water timers to human “alarm callers” — to wake up on time.

Historians say the need for reliable wake-up systems grew significantly during the Industrial Revolution in Britain, when factory work demanded strict schedules. Even a few minutes’ delay by workers could disrupt production lines, yet early alarm clocks were expensive and beyond the reach of most labourers.

As a result, a unique profession emerged in many industrial towns: the “knocker upper.” These individuals would walk through streets early in the morning, tapping on windows with long sticks or shooting dried peas through pipes to wake their clients.

Historian Arunima Datta said these human alarm clocks would remain outside until they received confirmation that the person inside had woken up.

Similar practices existed in other parts of the world as well. In some Muslim communities during Ramadan, people traditionally woke others before dawn so they could pray and eat the pre-fast meal.

Before such organised wake-up services, people often relied on natural signals to start their day. According to sleep researcher Fatima Yaqoot, daylight was one of the strongest cues guiding sleep and waking patterns in many pre-industrial societies.

Animals also played a role. The crowing of roosters at dawn served as a natural alarm for many communities, while the morning “dawn chorus” of birds signalled the start of the day.

Timekeeping devices were also used centuries before modern alarm clocks. Historian Sasha Handley notes that people used various technologies to help regulate their daily schedules, especially for work or religious practices.

In medieval Europe, church bells rang regularly to mark the hours and guide daily activities. In households, servants were often responsible for waking their employers at the appropriate time.

Elsewhere, people developed ingenious mechanical solutions. In ancient China, candle clocks marked time with metal pins embedded in the wax. As the candle burned down, the pins dropped into a tray, creating a sound that could wake a sleeping person.

Incense clocks used a similar principle, sometimes releasing small metal balls that struck a tray when burning threads snapped. Meanwhile, water clocks — known as clepsydras in ancient Greece — could trigger sounds when rising water pressure forced air through a tube.

The philosopher Plato is often credited with adapting a water clock into an early alarm system in the 5th century BC.

Mechanical clocks later improved timekeeping from the late 13th century onward, eventually leading to the development of domestic clocks with alarms. However, these devices remained costly and uncommon for ordinary people for centuries.

During the 19th century, the knocker-upper profession flourished in industrial cities such as Leeds, Manchester and London. These workers often began their rounds as early as 3am, ensuring factory workers woke in time for their shifts.

The profession gradually disappeared by the 1920s as alarm clocks became cheaper and more reliable.

Researchers say studying historical sleep habits offers useful lessons even today. Exposure to morning daylight and maintaining regular sleep schedules — practices common in earlier societies — are still considered important for healthy sleep patterns.