January Neatherlin told parents they couldn't pick up their children from Little Giggles childcare centre in the small US city of Bend, Oregon, between 11am and 2pm. That three-hour period, she said, was nap time.

It was also CrossFit time and tan time for Neatherlin, the owner of the illegal childcare operation, according to court records obtained by The Oregonian. In one instance, police investigators say, it was also drop-her-own-kids-off-at-school-time.

To avoid the risk that the seven infants and toddlers in her care would wake up, trudge around and possibly hurt themselves while she ran errands, Neatherlin drugged them with melatonin.

DESCHUTES COUNTY SHERIFF'S OFFICE January Neatherlin, 32, would leave children at her illegal childcare centre unattended so she could run errands.

Neatherlin, 32, was sentenced to more than 21 years in prison last week after she pleaded guilty to 11 counts of first-degree criminal mistreatment and one count of third degree assault in connection with Little Giggles, according to The Oregonian.

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Her scheme began to unravel last March when police were contacted by a former roommate and an ex-boyfriend.

Among other lies, Neatherlin told parents that she was a registered nurse, even though she wasn't, investigators in Bend, Oregon, testified.

It's unclear if she told them about her criminal record, which went back to 2007, when she was charged with "multiple instances of theft and identity theft," according to reports. Some of her convictions came under the aliases January Livsey and January Brooks.

Court documents said she had an "ongoing, systematic scheme of doing what she wanted and getting what she wanted, without any concern for the danger she was placing others in."

She operated Little Giggles for five years.

The court heard anecdote after anecdote of close calls and actual harm befalling the children Neatherlin was paid to take care of, according to The Bulletin. Some had disrupted sleep cycles from the melatonin, others fared much worse.

In January 2014, an 11-month-old was rushed to the hospital from Little Giggles with bleeding and swelling in her head, injuries court documents said were consistent with being shaken or struck repeatedly.

Parents of another child said the girl had blisters in her mouth and on her shoulders when she was picked up, The Bulletin reported. Neatherlin had overheated a bottle of milk in the microwave, scalding the child. When pressed, Neatherlin said the injuries were spider bites.

There were other causes of concern: nappy rash, allegations of scratching, evidence of poor nutrition.

When authorities moved in to arrest Neatherlin at her home 150 miles southeast of Portland, one of the children was covered in fresh vomit – and some of the children still had melatonin in their systems.

Melatonin is relatively safe, but it is not harmless. The Food and Drug Administration regulates dietary supplements such as melatonin, according to the National Institutes of Health (NIH), but rules are less strict than for prescription or over-the-counter drugs.

According to NIH, there have been "no reports of significant side effects of melatonin in children." And some companies even offer "sleep support" gummies with melatonin for children.

Still, the Mayo Clinic recommends that people take the hormone only after consulting with a doctor. The hormone can negatively interact with drugs that mitigate seizures, diabetes medications and "anticonvulsants in neurologically disabled children."

None of the children in Neatherlin's care appeared to be permanently damaged from the supplements.

In a tearful statement just before she was sentenced, Neatherlin denied that she had ever struck a child.

"I loved all my day-care kids as my own, and I believe they loved me and enjoyed hanging out with me during the week," she said.

But she also admitted that she had done wrong. "I failed you all. I let you all down."

Parents agreed.

"In my opinion, your honour," Kevin Hord, one of the fathers of the children in the childcare centre told the judge, "100 years would not be enough."

Hord and other parents lobbied for the maximum allowable sentence – 35 years. But a judge gave Neatherlin 21 years, four months and harsh words.

"There is something broken and something missing in you," Deschutes County Circuit Judge Wells Ashby told Neatherlin, according to the Bend Bulletin.

"It is sheer serendipity and chance that some of those kids were not killed."