sun was still rising at 09:00 and people travelled to work in the dark. Children also began the school day in darkness, with repercussions on their standards of learning, school performance and sleeping habits. It was even common that children fell asleep in the early morning classes. On summer evenings, the usage of Central European Summer Time was revealed to have a disturbing effect on peoples', especially children's, sleeping habits, as the sun was still setting as late as 22:30, so the sky was only completely dark towards midnight. A company hired by European Commission conducted a study which concluded that, in fact, there were no energy savings because, due to the dark early mornings, workers turned on lights in their offices and forgot to turn them off, leaving them switched on for the rest of the morning, which increased energy consumption. Concerns also emerged about the effect of the coincidence of rush hours with the hottest hours of the day on air pollution. Furthermore, an increase in the number of assaults on children in the morning was observed, and insurance companies reported a rise in the number of accidents. Due to all of these concerns and complaints, it became clear that situation could not continue much longer without a new analysis. In December 1995, the government (now led by António Guterres) commissioned a report to Lisbon Observatory on the issue of Portuguese standard time. In February 1996, the Observatory report was released and it concluded that owing to the geographical position of Portugal, the country should re-adopt Western European Time as its standard time zone, a position that the policymakers accepted. Return to Western European Time In 1996, new legislation was approved. By Decree-Law 17/96, mainland Portugal returned to the Western European Time time zone. DST would continue to be observed as WEST (UTC+01:00) from the last Sunday in March to the last Sunday in October, thus also adopting the then recently changed EU rules regarding DST. In the same year, Azores and Madeira regional parliaments also approved regional laws that adapted the new EU rules to their time zones, thus ensuring that DST would be observed from the last Sunday in March to last Sunday in October in the entire Portuguese realm. Date and time notation In 1996 Portugal adopted ISO 8601 via EN 28601 as NP EN 28601:1996. Time signalling The Astronomical Observatory of Lisbon publishes the