The sleeping position is the body configuration assumed by a person during or prior to sleeping.
It has been shown to have health implications, particularly for babies. Research by Chris Idzikowski, the director of the Sleep Assessment and Advisory Service, has suggested that the choice of position may indicate the type of person the sleeper is.
Sleeping habits in the population
From his survey of 1000 people, Idzikowski identified six positions and claimed to detect personality traits based on them:
- Fetus (41%) – curling up in a fetal position. This was the most common position, and is especially popular with women.
- Log (15%) – lying on one's side with the arms down the side.
- Yearner (13%) – sleeping on one's side with the arms in front.
- Soldier (8%) – on one's back with the arms pinned to the sides.
- Freefall (7%) – on one's front with the arms around the pillow and the head tilted to one side.
- Starfish (5%) – on one's back with the arms around the pillow.
The remaining 11% stated their position varied or did not know. A Canadian survey found very different preferences, with 39% of respondents preferring the "log" position and 28% preferring to sleep on their side with their legs bent.
It has been noted that combinations of sleeping positions are related to level of intelligence. Those who sleep in a log/foetus position have been proven to be most intellectually advanced. 
A Travelodge survey found that 50% of British couples prefer sleeping back-to-back, either not touching (27%) or touching (23%). Spooning was next, with the man on the outside 20% of the time vs. 8% with the woman on the outside. 10% favored the "lovers' knot" (facing each other with legs intertwined), though all but 2% separated before going to sleep. The "Hollywood pose" of the woman with her head and arm on the man's chest was chosen by 4%.
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,[clarification needed] 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[clarification needed] and might have prevented over 10,000 infant deaths in the UK and at least 50 000 in Europe, the USA, and Australasia."
Pregnancy.org champions sleep on side (SOS), particularly the left side, for pregnant women, claiming this "will increase the amount of blood and nutrients that reach the placenta and your baby." A couple of research papers also link sleeping on your back during pregnancy with lower birth weight and increased risk of stillbirth, but these results must be corroborated by other larger studies.
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.
The Chinese feng shui and Indian Vastu Shastra systems describe favorable and unfavorable geographical directions (north, south, east, west) for sleeping. Feng shui also factors the configuration of the bedroom in the positioning of the bed.
Traditionally it is believed that the person who sleeps should place his head to north. Some people say it is good to avoid head to the south. Also there are beliefs which say that the person who places head to east learns quickly and the person who places head southwards remains virtuous, whereas west placing results in worrying and north to losses.
It should be noted that these claims are not backed-up by scientific evidence and that there is no theoretical foundation for these effects to take place.
- "Sleep position gives personality clue". BBC News. 16 September 2003.
- "Good health rests on a good night's sleep". CBC News. 11 June 2007. Retrieved 1 May 2010.
- "Couples' sleeping poses uncovered". BBC News. 7 October 2006. Retrieved 1 May 2010.
- Ruth Gilbert, Georgia Salanti, Melissa Harden and Sarah See (2005). "Infant sleeping position and the sudden infant death syndrome: systematic review of observational studies and historical review of recommendations from 1940 to 2002", International Journal of Epidemiology, Oxford University Press.
- "Sleeping Positions During Pregnancy". Pregnancy.org. Retrieved 1 May 2010.
- Stacey et al. (2011). "Association between maternal sleep practices and risk of late stillbirth: a case-control study". BMJ 342.
- Owusu et al. (2013). "Association of maternal sleep practices with pre-eclampsia, low birth weight, and stillbirth among Ghanaian women". International Journal of Gynecology & Obstetrics 121 (3): 261–265. doi:10.1016/j.ijgo.2013.01.013.
- "Obstructive sleep apnea - Lifestyle Changes". University of Maryland Medical Center. Retrieved 1 May 2010.
- Neill et al. (January 1997). "Effects of sleep posture on upper airway stability in patients with obstructive sleep apnea". American Journal of Respiratory and Critical Care Medicine 155 (1): 199. Retrieved 1 May 2010.
- "Snoring and Sleep Apnea". American Association of Oral and Maxillofacial Surgeons. Retrieved 1 May 2010.
- David Daniel Kennedy. "Applying Feng Shui Principles to Your Bed". Dummies.com. Retrieved August 22, 2010.