Sleep in piglets: An observational study

Abstract

The development of sleep was examined in 16 piglets during their first 5 weeks of life. Each piglet was observed for one 90 min period each week and a record of the duration of lying, non-REM-sleep and REM-sleep was made. Sleeping position was also recorded. The amount of time spent sleeping and lying did not change systematically over the 5 weeks and neither did the duration of a sleeping episode. However, the duration of REM-sleep decreased from Week 1 to Week 5. REM-sleep could readily be divided into bouts and whereas the median bout length, number of bursts of REM-sleep per bout and duration of each burst remained constant, the mean number of bouts per observation period showed a marked decline with age. REM-sleep was seen to occur more frequently in the crouch position (all 4 legs folded under the body) than in any other position. It was concluded that the development of sleep follows a similar pattern to other precocious and non-precocious species and that piglets are probably not sleep-deprived.