Yes, if your period starts at night, that day is considered day 1 of your menstrual cycle.
According to the provided reference, day one of your cycle is the first day of your period. It doesn't specify a time of day. Therefore, regardless of whether your period starts in the morning, afternoon, or night, that day is considered day 1.
Here's why that is:
- Tracking purposes: The first day of your period is the easiest and most reliable marker to track your cycle.
- Hormonal shifts: The start of menstruation signifies a significant shift in your hormone levels, prompting the beginning of a new cycle.
In summary, the time of day your period begins does not change the fact that the first day of bleeding is always considered day 1.
