“Did you get enough sleep last night?”

The short answer is almost always no, these days. Sleep deprivation is no longer news, even though it created ripples in 2009 when it was first reported that 93% of Indians don’t get enough shut-eye.

But the long answer – why – is what’s interesting. And understanding of it is still evolving.

“The advent of artificial light has increased our day to 24 hours. The demarcation between day, meant for work, and night, for sleep, is blurring increasingly,” says Dr. Sanjay Manchanda, consultant, sleep medicine, at Delhi’s Sir Ganga Ram Hospital. “But we don’t understand the limitation of the human body, which, under such pressure, somehow functions but doesn’t perform.”

Among the myriad types of light that evenings come aglow with, blue light – that is, blue wavelengths in the light spectrum – is the most harmful. Found naturally until sundown, blue light is what helps us stay alert. Our bodies respond to it by suppressing melatonin, the hormone that influences our sleep cycle. Unfortunately, blue light is just as prevalent at night, too. Emanating from artificial sources like smartphones and laptops – even from energy-efficient CFLs and LEDs according to one Harvard study – it tricks our brain into believing it’s daytime.

“The backlit screen not just delays sleep but also lowers its quality,” says Dr. Dayal Mirchandani, a Mumbai-based consulting psychiatrist and author. “People also tend to watch videos on their laptops and phones these days, which is worse than watching TV that’s usually done from a distance.”

While blue light is the worst culprit, other light suppresses melatonin, too. This compounds the toll of the modern, late-night corporate grind.

“Bankers were envied for their 9 to 5 jobs, but that (schedule) is a thing of the past,” says Dr. Mirchandani. “Pilots and flight attendants used to get four to five days off between a shift change; not anymore.”

Much of urban India takes lengthy commutes only to operate on a late-start, late-finish schedule that not only leaves little time for relaxation but one also at odds with the body’s circadian rhythm. Popular jobs, like those in call centres, often require a night shift, which confuses the body further, says Dr. Mirchandani, even when alternated with a day shift.

The peril is profound; a growing body of evidence shows that night shift workers are at increased risk of cardiovascular, gastrointestinal, and reproductive disorders, above and beyond the myriad health problems sleep deprivation has been linked to among the general day-working population.

And as with most problems here, there’s a gender angle, too. After all this, Dr. Mirchandani says, men generally have it easy when they finally reach home.

“But women, in general, always work in double shifts as household work, even with help, is their domain by default,” he says.

For some, this culture of sleep deprivation has turned into a cult of sleep deprivation, as figures like Shah Rukh Khan and even PM Modi, who both claim to need only a few hours’ sleep each night, make sleeplessness appear a path to success. Dr. Mirchandani says patients have admitted to trying to reduce their sleep to as little as four hours in order to accomplish more.

But whether the cause is scientific, cultural or corporate, what’s getting overlooked is the fact that anything that curtails hours of sleep is also damaging quality of sleep.

“Among children and teens, this (deep sleep) is the time when the body secretes maximum growth hormone, and for adults, deep sleep is crucial because that’s when the body heals itself,” says Dr. Manchanda. “Any stimulus, external or internal, that causes a break in sleep prevents you from going into deep sleep.”

So what’s the way out of what many other sleep-deprived countries are calling a public health problem?

There could be a couple of solutions. Tech companies, whose products are emitting the very blue light that keeps us awake all night, are developing and offering add-on screens and glasses that filter out the blue light, though these don’t appear to be available domestically for anything other than an Apple product yet.

Others are advocating a need to rethink the way we sleep. A theory called ‘segmented sleep’ – in which a person sleeps for four hours, wakes for one to two, then sleeps for another four – is gaining popularity. The idea hit mainstream consciousness in the early 2000’s, when historian Roger Ekrich published a book that documented how humans followed this mode of sleep for much of known history.

But until either option is proven, medical advice remains the same, Drs. Mirchandani and Manchanda say: Close the laptop, turn off the phone, and get eight hours of sleep.