Late nights, long sleeps, low output: Workers who don't follow a social schedule struggle most at work, finds a study

A large study tracking sleep through smartphones has found that workers whose body clocks clash with social schedules, often called “social jetlaggers”, lose the most productivity at work. The analysis, based on sleep data from nearly 80,000 Japanese workers, also shows that people prone to insomnia face a similar dip in performance. Researchers say both too little and too much sleep can quietly drag down workplace output.

What the study found
Researchers from the University of Tsukuba studied smartphone-collected sleep data and matched it with productivity loss scores gathered through questionnaires. They looked closely at total sleep time, how long people took to fall asleep, and how often they woke up during the night.


The results, published in the journal npj Digital Medicine, point to a clear U-shaped pattern. Workers who slept for very short hours and those who slept for unusually long hours both showed reduced productivity at work.

In simple terms, extreme sleep habits on either side came with a cost.

Who are the “social jetlaggers”?

Social jetlag happens when a person’s internal body clock does not match their daily work or social schedule. For example, sleeping late and waking late on weekends, then forcing an early routine on weekdays, can throw the body out of sync.

The researchers grouped participants into five sleep types, or phenotypes: “healthy sleepers”, “long sleepers”, “fragmented sleepers”, “poor sleepers” and “social jetlaggers”.

Among these, two groups stood out for all the wrong reasons.

The worst-hit sleep groups

“The latter two clusters showed the worst scores for insomnia, daytime sleepiness, and presenteeism (reduced workplace productivity),” they said.

People in these groups often took longer to fall asleep, woke up frequently during the night, and showed greater misalignment between their sleep timing and daily routines. All of this added up to lower performance at work.

The team also found that frequent night awakenings and irregular sleep patterns mattered just as much as the total number of hours slept.

It’s not just about hours in bed

The findings underline a broader message: sleep quality, timing and regularity play a major role in how people function at work. Simply clocking more hours does not guarantee better productivity.

Workers who slept at odd hours or followed inconsistent routines were more likely to struggle during the day, even if their total sleep time looked “normal” on paper.

Why smartphones matter here

The researchers say smartphone-based sleep tracking could help spot people at risk on a large scale. Such tools may guide more personalised strategies in the future, helping workers adjust sleep habits before productivity takes a hit.

For now, the message is clear and slightly ironic for a busy world: sleeping too little, too much, or at the wrong time can quietly undo your best efforts at work.

(Source: PTI)