<P> In India, the culture has always said that when you wake up, you must roll to your right side and then get out of bed . According to the Ayurveda, this can reduce the pressure on the cardiac system which constitutes of heart on the left side of the body . </P> <P> The Indian Vastu Shastra and Chinese Feng shui systems describe favorable and unfavorable geographical directions (north, south, east, west) for sleeping . Vastu Shastra suggests not to sleep towards North for people living in Northern hemisphere and not towards South in case of Southern Hemisphere . Blog by Sadhguru (Isha Foundation) quotes, "East is the best direction . North - east is okay . West is alright . South, if you must . North, no . This is true as long as you are in the northern hemisphere--sleeping with your head towards any side except north is okay . In the southern hemisphere, don't put your head to the south ." </P> <P> Feng shui also factors in the configuration of the bedroom in the positioning of the bed . In Islamic culture, some sleep positions are encouraged while others are discouraged based on the practice (Sunnah) and recommendations of Muhammad . Thus, many Muslims sleep on their right side, particularly, in the initial part of sleep . Muhammad said, "Whenever you go to bed, perform ablution like that for the prayer, and lie on your right side" (SM 2710). In description of the sleep of Muhammad, a Hadith states, "When the Prophet (pbuh) wants to go to sleep, he puts his right hand under his cheek" (SM 2713). Modern scientific studies have suggested a beneficial effect of right lateral decubitus position on the heart . In particular, one study assessed the autonomic effect of three sleep positions (supine, left lateral decubitus, and right lateral decubitus) in healthy subjects using spectral heart rate variability analysis. The results indicated that cardiac vagal activity was greatest when subjects were in the right lateral decubitus position . </P>

Should you sleep north to south or east to west