(Your contact information)
(Name of the Recipient)
(Address of the Recipient)
(Contact Information of the Recipient)
Sub: Letter to apologize for sleeping on duty
Dear (Name of the Recipient)
I really apologize for my irresponsible of sleeping during duty hours, which happened on the day of (mention the details of the issue). I am really regretful for my behavior and for the inconveniences it has caused you and your institution. I am really very sorry as I fell asleep, but it was really unintentional on my part. As I take full responsibility for the mistake from my side, I am assuring you that this mistake will not repeat itself again in the future. I feel regret for the problems you and your institution had to face for my nonsensical attitude.
I would really appreciate this if you consider my problem and circumstances which is the main cause of my faulty behavior. I hope you will give me another chance to prove myself and my qualities.
I am ready to receive the result of this mistake caused by me. If you have anything to say to me regarding this matter you can contact me at any time. I am always ready to be in touch with you. Hope you will consider my request and oblige me.
Thank you for your kindness and support like always,
(Notary or witness if required)