Answer
It is Sunnah for both men and women to begin their sleep on the right side.
In an Aayat of the noble Qur’aan, Allah Ta’ala states, ‘Your wives are a
tilth for you, so go to your tilth (have sexual relations with your wives in
any manner as long as it is in the front opening and not in the hind
opening).’ (Baqarah Aayat223)
In a Hadith narrated by Ibn Abbaas (Radhiallaahu Anhu), the above Aayat was
revealed to Rasulullah (Sallallaahu Alayhi Wasallam), ‘Go from the back or
from the front but stay away from the hind opening and at the time of Haydh
(menstruation).’ (Mishkaat pg.276)
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai