Hamlet said “To be or not to be” instead of “To sleep or not to sleep” for good reason. The first is an all-consuming question — especially if your ghost of a dad tells you to avenge his murder.

The second requires no reflection regardless of what your phantom or flesh-and-blood father requests.

Not to sleep — that is to say not to sleep sufficiently — should never be the question.

Yet skimping on sleep is so common that in 2014 the Centers for Disease Control and Prevention declared it “a public health problem.” They did so because research determined that nearly four out of every 10 Americans between the ages of 25 and 54 slept less than seven hours a night, with the overall adult average a mere 6.8 hours.

Sleeping less than seven hours a night has been linked to seven of the 15 leading causes of death, including heart disease, hypertension, and diabetes.

American adults didn’t always skimp on sleep. In 1910 — before smartphones, video games, television, or even radio — they averaged 9.0 hours of sleep, according to TheGoodBody.com.

But it’s not just adults who shortchange sleep today. Because teenagers require more of it, they are actually more sleep deprived than adults. TheGoodBody.com posits that 97 percent of all teenagers get less than their recommended amount of sleep, which, however shocking, might very well be true.

A 2006 survey by the National Sleep Foundation found 87 percent of surveyed high-schoolers fell short of the suggested eight to 10 hours per night.

Now whether you are sleep deprived at 15 or 55, one thing is true: Lack of sleep makes it easier to gain weight and tougher to lose it.

You would think the opposite is true. Since you burn more calories awake than asleep, staying up longer should make it easier to lose weight.

And it would — except the lack of sleep affects your body’s secretion of certain hormones.

During sleeping, your body produces higher amounts of leptin, the hormone that suppresses hunger in an effort to keep your sleep from being disrupted. Therefore, when your body experiences a reduction in leptin from a reduction in sleep, you begin to feel hungry when there’s really no need for food.

Even though the hunger sensation is a “mistake,” there’s no mistaking it. You eat. Unfortunately, eating unnecessarily as a result of being low on leptin actually leads to greater weight gain than overeating after a night of sufficient sleep.

Low levels of leptin also slow your metabolism and encourage your body to store fat. It makes sense. It’s the body’s attempt to keep feelings of hunger from disrupting sleep in the future.

The hormone seen as leptin’s opposite, ghrelin, the one that signals the need to eat, also gets adversely affected by insufficient sleep. Its production naturally drops while you sleep, so less sleep means less of a drop — and an increased likelihood of eating more than the needed amount food.

While no part of the renowned Nurses’ Health Study has focused on how a lack of sleep effects the secretion of leptin and ghrelin, it has done much to establish the correlation between insufficient sleep and weight gain.

One segment of it that took 16 years and studied about 60,000 women found that those who generally slept five hours per night had a 15 percent higher risk of becoming obese over the course of the study when compared to those who slept at least 7 hours per night. These short sleepers also had a 30 percent higher risk of gaining 30 pounds over the course of the study when compared to women who got 7 or more hours of sleep per night.

A study published in July in the International Journal of Obesity indicates just how damaging a lack of sleep can be to diets designed to produce weight loss. Spanish researchers working primarily at Rovira i Virgili University in Tarragona, Spain studied nearly 2,000 overweight senior citizens who willingly dieted and exercised in an attempt to shed excess fat.

The researchers found that after one year the subjects who had irregular sleep patterns lost less weight than those who did not. Moreover, those who tended to sleep less than 6 hours a night lost fewer inches from their stomachs than those who usually slept between 7 and 9 hours.

Yet everyone is different, so your own lack of sleep may not create excess weight or too large a tummy. What it is doing, however, is increasing your odds of a shortened lifespan.

A study published in 2107 by Rand Health Quarterly found that those who sleep on average less than six hours per night have a 13 per cent higher mortality risk than those who sleep between seven and nine hours. Those who sleep more than six but less than seven still have a 7 percent higher mortality risk.