Is there great sin on one who delays ghusl from menses due to illness and laziness until Fajr prayer is missed?

If a woman sleeps after the time for Fajr prayer has begun, and she is not certain she will wake up before the prayer's time expires, she commits a sin for neglecting the prayer time. However, if she is reasonably sure she will wake up before the time expires, or if her sleep began before the prayer time entered, then there is no sin upon her.