<P> In the 1958 edition of his best - selling book The Common Sense Book of Baby and Child Care, pediatrician Dr Benjamin Spock warned against placing a baby on its back, writing, "if (an infant) vomits, he's more likely to choke on the vomitus ." However, later studies have shown that placing a young baby in a prone position increases the risk of sudden infant death syndrome (SIDS). A 2005 study concluded that "systematic review of preventable risk factors for SIDS from 1970 would have led to earlier recognition of the risks of sleeping on the front and might have prevented over 10,000 infant deaths in the UK and at least 50,000 in Europe, the USA, and Australasia ." </P> <P> It is recommended that people at risk of obstructive sleep apnea sleep on their side and with a 30 ° or higher elevation of the upper body . Snoring, which may be (but is not necessarily) an indicator of obstructive sleep apnea, may also be alleviated by sleeping on one's side . </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, the worst . 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 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>

Where should your head be when you sleep
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