Carbon monoxide is an odorless, colorless, and tasteless gas that is near impossible to identify without a proper detector. It is caused by fuels not burning completely, including wood, gasoline, coal, propane, natural gas, gasoline, and heating oil.
The cause of lethargy may be suggested by its pattern and accompanying symptoms. If it starts in the morning and lasts all day, it could be due to lack of sleep or depression.
Hypoglycemia--also called low blood sugar--can cause specific symptoms to arise in your toddler, which you should discuss with your pediatrician if they occur.