Sleep in Early Childhood
Sleep: An Overview
Preschoolers oftren sleep 10 to 11 hours out of a 24 hour day.  This includes 9 to 10 hours at night and a nap of 1 to 2 hours.  School ag echildren typically need 9-10 hours of sleep, with the number decreasing as each year goes by.

Bedtime Routines are useful in helping a child transition from awake hours to bedtime sleep.  A transitional object, often a special blanket or stuffed animal, may be taken to bed with a child and will make the transition easier. 

Getting children to sleep each night can be a significant challenge in a household, leaving children with lost sleep.
Sleep Disorders of Early Childhood
Sleep Terrors and Nightmares:
Sleep terros (or night terrors, as they are someteims called) occur during deep sleep and during the early night hours.  Ty-cially outgrown by late adolescence, sleep terros typically begin occurring during the childhood or early adolescent years.  You will know a sleep terror may be occurring by the presence of increased heart and respiration rates, thrashing about, and talking incoherently. 

Nightmares, unlike sleep terrors, occur during lighter REM sleep and are experienced by adults as well as children.  They ar dconsidered 'normal' dreams, though undesirable.

Both Nightmares and sleep terrors may cause children to fear going to sleep, as evidencede by refusla to put on pajamas or insisting that the lights remain on durin ght enight.  Children need their parent's understanding and affection to cope with sleep terrors and nightmares. 
Sleep Walking/ Somnambulance:
Sleep walking occurs during deep sleep, like sleep terrors, and is more common in children than in adults.  Episodes of sleep walking are typcially brief, lasting less than half an hour.  Sleep walking is believed to be an immaturity of the nervous systerm, rather than an acting out of dreams or psychological conflicts.
Cross-Cultural Differences in Sleeping Arrangements
While children in the USA typically sleep in separate beds, and often separate rooms, from their parents, children in other cultures sleep with their mothers for the first years of their lives in the same room and often in the same bed.  This practice, known as co-sleeping, occurs in both technologically advanced and technologically dperessed areas of the world.  The resistance tin going to bed that occurs among 20-40% of American preschoolers and infants is seldom seen in cultures that practice co-sleeping and is seen by some psychologists to be caused by the stress of separating from parents.  Co-sleeping has not revealed any harmful effects, according to research, and has the effect of decreasing a child's need for a transitional object such as a blanket or stuffed animal.  In fact, research has shown tha tco-sleeping is connected with greater social independence in some cultures.
To Summarize....
Young children need significantly more sleep than adults but also have more sleep difficulties than adults.  Some sleep diffficulties that may occur include sleep terrors, nightmares, and sleep walking.  These difficulties of sleeping in early childhood may be correlated to difficulties in getting children to go to bed.   Children may use a transitional object, such as a special blanket or stuffed animal, to aid in going to bed at night.  Some cultures have adopted co-sleeping, which allows a child to sleep in the same room andsometimes in the same bed as their mother, which decreases difficulties in going to sleep.  Regardless of their culture, preschoolers need to sleep for 10 to 11 hours out of 24 and will be unable to make up for lost sleep.
"Rock-a-bye baby, on the tree top.  When the wind blows the cradle will rock.  When the bough breaks, the cradle will fall.  Down will come baby, cradle and all." 
       -  Traditional American Lullaby
REFERENCE:
Rathus, S. (2006).  Childhood: Voyages in Development, Second Edition (pp. 20-282).  Canada:  Thomson Wadsworth.