But as people age, they tend to spend less time in deep sleep stages, sometimes skipping them altogether. (mattressadvisor.com)
Every normal individual has the majority of his / her growth hormone released during deep sleep stages. (fitnessandpower.com)
Around 4 months, as sleep becomes more «adult - like», your baby will not enter immediately into that non-REM deep sleep stage as soon as they fall asleep. (weebeedreaming.com)