I'm not sure I understand your first question. Do you mean it takes a few hours for you to really notice the flow? If so, this is just the way the body works. Periods tend to be heavier the 2nd and 3rd days, and taper off afterwards, and the first day's flow can be lighter. What you're seeing is just your body's normal progression.
The flow can appear to lessen @ night and during physical activity as well, yes. But it's still there.
Could you have seen this article? The 4th paragraph talks about getting relief from menstrual symptoms.
Copyright 1998, 2014 Heather Corinna/Scarleteen
Scarleteen.com: Providing comprehensive sex education online to teens and young adults worldwide since 1998
Information on this site is provided for educational purposes. It is not meant to and cannot substitute for advice or care provided by an in-person medical professional. The information contained herein is not meant to be used to diagnose or treat a health problem or disease, or for prescribing any medication. You should always consult your own healthcare provider if you have a health problem or medical condition.