The PSQI total score represents the sum of component scores for subjective sleep quality, sleep latency, sleep duration, sleep efficiency, sleep disturbances, use of sleep medicine, and daytime dysfunction. A PSQI score >5 defined poor sleep quality. Higher scores implied lower sleep quality or more severe sleep disturbance.

Sleep assessment was a major part of the study. A 7-day assessment of mothers' sleep quality was conducted during the third trimester by using Actiwatch (Respironics, Inc.1001, Actiwatch 2) and sleep diary. Actiwatch is a sleep assessment system based on monitoring individual activity whose evaluation point is based on the sleep diary.

Sleep assessment was a major part of the study. A 7-day assessment of mothers' sleep quality was conducted during the third trimester by using Actiwatch (Respironics, Inc.1001, Actiwatch 2) and sleep diary. Actiwatch is a sleep assessment system based on monitoring individual activity whose evaluation point is based on the sleep diary.

Infant sleep problems reported by the mother and according to Brief Infant Sleep Questionnaire (BISQ). It is not a scale. The variables of the questionnaire included 1) nocturnal sleep duration (between the hours of 7 pm and 7 am); 2) daytime sleep duration (between the hours of 7 am and 7 pm); 3) number of night wakenings; 4) duration of wakefulness during the night hours (10 pm to 6 am); 5) nocturnal sleep-onset time (the time when the child falls asleep for the night); 6) settling time (latency to falling asleep for the night); 7) method of falling asleep; 8) location of sleep; 9) preferred body position; 10) age of child; 11) gender of child; 12) birth order; and 13) role of the responder who completed the BISQ. If the child woke up more than 3 times per night, spent more than 1 hour in wakefulness during the night, or spent less than 9 hours in sleep (day and night), then they were considered as poor sleepers.