Actress Blake Lively, who is the mother of three kids under the age of 5, says she'll sleep when she's dead.

While we sympathize with the grueling routine that motherhood demands, we hope she's finding a way to get more rest. Her health, longevity, and happiness depend on it.

But we have a theory about what — besides her active trio — may be contributing to Blake’s sleeplessness. It turns out that she's a big fan of having a sweet treat before bedtime.

A new study in the American Journal of Clinical Nutrition reveals that eating carbs before bedtime contributes to insomnia.

The researchers found that the worst culprits are refined carbs with a high glycemic index. That includes ice cream, soda, cookies, chips, and candy.

Such foods make your blood sugar spike, causing insulin to be secreted. Then your blood sugar drops quickly, stimulating the release of energizing hormones like cortisol and adrenaline.

Then guess what? You're awake.

Because 30% of Americans contend with insomnia, and the U.S. is an avid snacking nation — 62% of people snack throughout the day, and almost 50% have four or more snacks daily — we're betting late-night noshing is keeping a lot of folks awake.

If you need a bite of something before bed, try a slice of an apple or a pear (not a whole one) with a teaspoon of peanut butter on it. That touch of complex carbs with protein should keep the snack from keeping you up.

And you’ll feel a lot more Lively in the morning if you lay off the bedtime sweets.