Member States may lay down:
(a) for the application of Article 5 (weekly rest period), a reference period not exceeding 14 days;
(b) for the application of Article 6 (maximum weekly working time), a reference period not exceeding four months.
The periods of paid annual leave, granted in accordance with Article 7, and the periods of sick leave shall not be included or shall be neutral in the calculation of the average;
(c) for the application of Article 8 (length of night work), a reference period defined after consultation of the two sides of industry or by collective agreements or agreements concluded between the two sides of industry at national or regional level.
If the minimum weekly rest period of 24 hours required by Article 5 falls within that reference period, it shall not be included in the calculation of the average.