It is always interesting to hear people at work boast about how little sleep they got the night before. At times, I too must confess to being guilty on this count. It appears almost to be a badge of honour among top executives to say, “I slept only four hours last night and, look at me, I am at work this morning.”

Donald Trump repeatedly bragged about not needing much sleep while needling his opponents for being low on energy and lacking stamina. Margaret Thatcher and Bill Clinton are often evoked as successful people who reportedly slept only four hours a night on a regular basis. Sam Walton, the founder of Walmart, got to work at 4 am every day. This made me feel ashamed that I used to arrive only by 6 am at Harvard, IMD and London Business School, all places where I knew the cleaning staff on a first-name basis.

Given that we would send a truck driver home if we knew he or she had just four hours of sleep the previous night, I am surprised we do not tell top executives the same. While they may not be operating a heavy vehicle that can crash because fatigue lowers responsiveness, the decisions that managers make can affect thousands of lives.

Research has documented that sleeplessness leads to slower mental functioning. The lack of sleep makes it harder for an individual to sustain attention and maintain peak cognitive performance. Studies demonstrate that sleeplessness lengthens response time, impedes judgement and interferes with effective problem solving. And, over the long term, lack of sleep is associated with all types of maladies, from high blood pressure to obesity.

There is an interesting line of research on the need for sleep. If we go back to our hunter-gatherer days, we were most vulnerable to being attacked when asleep. Even when aroused from sleep to any danger, our reaction time is slow since our muscles are muted from inactivity. Consequently, sleep must have some overwhelming functional benefits for us to have put ourselves in such danger.

Overnight therapy

Not just humans, but all animals sleep. There are several streams of research that reveal the psychological and physiological benefits of sleep. Simply put, it is overnight therapy.

Psychologically, through sleep we process memory in a way that helps recalibrate our emotional self. Experiments show that during sleep, we separate significant experiences from the emotional baggage associated with them. This allows us to recall these experiences, and their information-rich content, without the associated emotion (especially pain).

Physiological research shows that during sleep, the body recharges itself physically, with brain and body engaging in important repair functions. Brain scans indicate that during sleep, the brain flushes unnecessary matter and fixes systems that are put under stress during the waking hours.

Sleep therapists recommend getting eight hours of sleep a night. However, as both parents are increasingly employed outside the home, and the household chores still have be done within the same 48 hours a day that are available to the couple, lack of sleep is becoming a societal problem. Companies and managers are not helping by pushing for long hours at the workplace.

While I do not come in to work at 6 am anymore, I am still careful to leave work at a reasonable hour because I am acutely aware of the knock-on effects on my team. Those reporting to me will usually not leave until I do so. On joining the Tata Group, I asked one of our smart young executives what the official working hours were. She quipped: Ten minutes before your boss comes in, and until 10 minutes after they leave.

And, as top executives often do not realise, the commute of those lower down the food chain is usually longer and they have less help available at home. Furthermore, nowadays, the bane of always being connected is that, at least from my own experience, one ends up spending on average an hour a day on work emails between leaving and returning to the office.

All of this means that if you, as a top executive, are pushing people to work late hours, they are physically unable to have their eight hours of sleep. Without sleep, productivity suffers, creative thinking declines and overall irritability increases – across the organisation.

In conclusion, let us stop boasting about how late we stayed in the office. It does nobody any good. There is no need to show how important we are by the amount of hours we work. Instead, why not use our time in the office efficiently, delegate more, and have some wakeful empathy for those working under us?

Nirmalya Kumar is Member-Group Executive Council at Tata Sons and Visiting Professor of Marketing at London Business School. His Twitter handle is @ProfKumar. This article is written in his personal capacity.