Many secondary doors that caregivers use were left open in the past.
Those doors, which many may not even notice, now require a keycard for entry.
The hospital has 52 doors to the outside, most of which will now be kept locked at night.
The only doors left for entry after 8pm will be for the emergency department.
Those with Heartland security say the new measures are not related to any incident; they are proactive.
"We try to provide a 5-star service in our clinical care," said Shawn Henderson from Heartland's security team. "We try to have that same high bar for the security and welfare for all those who visit, whether it's a patient, a loved one, or a caregiver. It's our responsibility to make sure that's in place."
At the Maternity department, the doors will also be locked, but patients can be buzzed in by pressing a button at that entrance.