If you want to provide an explanation for your absence without directly admitting that you overslept, you can consider using a more general excuse that avoids specifying the reason. Saying "I got my days confused. I thought it was Saturday" is one way to approach it, but keep in mind that honesty is generally the best policy, and it's essential to be cautious when using excuses that are not entirely truthful.
If you decide to use this excuse, be prepared to accept any consequences that may arise from it, especially if your boss finds out the truth or if they question the validity of your explanation.
Another option is to be more general in your explanation and express remorse for the oversight. For example, you could say:
"I apologize for not being able to make it to work this morning. I had an unexpected situation that I needed to attend to. I understand the importance of being present at work and will take measures to ensure this doesn't happen again."
By taking responsibility for your absence and expressing remorse, you show professionalism and a willingness to improve. Remember that consistent tardiness or absence can impact your professional reputation, so it's essential to make an effort to avoid future incidents. Consider setting multiple alarms or implementing other strategies to help you wake up on time. If you're facing difficulties that affect your punctuality regularly, it may be helpful to discuss the issue with your boss to explore potential solutions together.