A staff member will be considered a night worker if they normally work at least 3 hours or more between 22:00 and 07:00, or are expected to work 30% of their annual working time during these hours.
If an employee qualifies as a night worker, the maximum working hours per day must not exceed 8 hours on average over a reference period of 15 days. This means that the employee can work over 8 hours on a day as long as the daily average working time (over a consecutive 15-day period) does not exceed 8 hours per day.
More information can be found on the Portuguese official website on the following link: https://portal.act.gov.pt/Pages/Home.aspx