In a way this is one of those scientific studies that you’re amazed we needed. But who knew the impact lasted so long?

As any parent knows, a full night’s sleep is a thing of the past when your new sweet darling comes home. Yes, a few are perfect angels from Day One.

But for most parents there’s this hunger thing with tiny tummies. And gas. And a full diaper. And gums that hurt. And a dog that barks just as the little one’s eyes finally close.

It’s worth it in the long run of life, of course. But in the short run? Well, that’s something else.

Researchers found that on average fathers of newborn babies lose about 13 minutes of sleep a night, sometimes more during the most trying first three months of parenthood when eating and sleep routines are first formed.

Of course, sleep disturbances vary by baby and can erupt more often and last longer than average.

As traditional primary caregivers, mothers of newborn babies lose on average a whopping 62 minutes of sleep a night. Apparently, there’s this thing called nursing that fathers are unqualified to do.

But here’s the British university’s research finding that surprised:

Even six years later, when the baby is in first grade, the toll of sleep disturbances and deprivation persist. The study’s co-author, Dr. Sakari Lemola, wrote:

While having children is a major source of joy for most parents, it is possible that increased demands and responsibilities associated with the role as a parent lead to shorter sleep and decreased sleep quality even up to 6 years after birth of the first child.

Even 72 months after the happy day, parental responsibilities are still taking a physical toll. Moms have somewhat recovered and regained about 40 of the 62 minutes of lost sleep per night. But — wait for it — the father is still losing a quarter-hour of sleep.

That’s two hours of lost sleep per week per parent. With one child.

Such sleep deprivation effects are most pronounced in first-time parents. But age, family income and single- vs two-parent households had no apparent impact.