Unprotected sleep is going back to sleep after turning off your alarm clock, risking not waking up for a job, class, or other daily task.
It is necessary for someone to have an unprotected sleep after staying up late or working late. It might also be delightful to have an unprotected sleep in weekends or holidays. However, unprotected sleep can be harmful to one’s health as it may disturb your biological clock, resulting in your short memory and blunt responsiveness.
After twenty minutes of unprotected sleep I missed the bus and had to walk to school.