The sudden death of a teacher who has been marking papers all night is an industrial injury. Death due to sudden illness during working hours and on the job is regarded as work-related injury. Overnight examination belongs to overtime work, so this situation belongs to sudden illness during working hours and on the job due to work reasons.
 [Legal Basis]
 Article 15 of the Regulations on Industrial Injury Insurance stipulates that an employee who has one of the following circumstances shall be deemed as an industrial injury:
 （1） Death due to sudden illness or death due to ineffective rescue within 48 hours during working hours and post;
 （2） Injured in activities of safeguarding national interests and public interests such as rescue and disaster relief;
 （3） An employee who was formerly serving in the army and was injured and disabled in war or on duty, has obtained a revolutionary disabled soldier certificate, and has suffered a recurrence of old injuries after arriving at the employer.
 In case of any of the situations mentioned in Items (1) and (2) of the preceding paragraph, the staff and workers shall enjoy work-related injury insurance benefits in accordance with the relevant provisions of these Regulations; In case of the circumstance mentioned in item (3) of the preceding paragraph, employees shall enjoy work-related injury insurance benefits other than one-time disability subsidies in accordance with the relevant provisions of these Regulations.