Abstract
Purpose
The purpose of the study was to determine the number of days of diary data collection needed to reliably measure mother and infant sleep-wake pattern.
Study Design and Methods
Twenty healthy adult mothers and their healthy term gestation infants age 4 to 10 weeks postnatal age participated in a single group, cross-sectional design. Mothers completed a paper and pencil sleep-wake diary divided into 15 minute time periods. Data were collected in the home environment over a four days period. Mother and infant sleep and wake as well as infant feeding and cry were summarized and compared using between one and four days of data. Reliability was evaluated by correlating results obtained using from one to four days of data.
Results
Mean values for mother and infant sleep and activity variables did not differ significantly by day. Correlation among values calculated using increases in number of days of data showed adequate reliability (r ≥ 0.80) when three days of data were used.
Clinical Implications
Clinical measures should be valid and reliable. Due to day-to-day changes in maternal and infant sleep-wake pattern, a diary collected over one day may not provide adequate sleep information. Study findings indicate that three days of diary data were sufficient to reliably measure mother and infant sleep pattern. When using a diary to assess maternal and infant sleep-wake pattern in clinical practice or clinically-based research, a three day period is suggested.
Keywords: mothers, infant, sleep, maternal-child nursing, methods
Introduction
Mother and infant sleep are a paramount concern in infant and maternal health nursing. Sleep loss among mothers is a significant health issue (Lam, Hiscock, & Wake, 2003; Thomas & Wang, 2005) and increasing evidence suggests that mother’s sleep pattern is instrumental in shaping that of her infant (Feldman, 2006; Nishihara, Horiuchi, Eto, & Uchida, 2002; Wulff, Wulff, & Siegmund, 2002). Assessing sleep is an essential component of clinical practice (Lee & Ward, 2005) and. daily diaries provide a direct measure of sleep-wake (Darlington & Wright, 2006; Symon, Marley, Martin, & Norman, 2005). Sleep-wake diaries are an effective means of assessing mother and infant sleep pattern in the home environment and are used to collect information in both nursing practice and clinical research. Sleep-wake diaries inform lactation consultation as well as ambulatory neonatal, pediatric, and maternity nursing care. Diaries however, raise the question, “How long should data be collected?”
The purpose of this research was to evaluate the number of days of diary data needed to reliably estimate mother and infant sleep-wake pattern. Specific aims included: (1) Describe daily mother and infant total sleep, number of sleep periods, and longest and mean sleep period. (2) Describe daily infant feedings and crying including total time, number of periods, and longest and mean length. (3) Compare mother and infant sleep, as well as infant feeding and cry measures, using incremental increases in number of diary days to determine minimum duration of data collection. (4) Assess reliability of incremental increases in number of diary days to determine minimum duration of data collection.
A diary is defined as an annotated chronological record or log maintained over time according to predetermined instructions (Richardson, 1994). Diaries are a simple, economic, and effective means of documenting real time patterns of human daily health behavior. In a classic review, Richardson (Richardson, 1994) outlined the advantages and disadvantages of health diaries. Diaries provide rich, dynamic, and prospective information about human health behaviors, reduce the loss of information that can result from problems with recall, and are time-ordered allowing health practitioners to evaluate connections between factors over time (e.g., the relation between infant feeding and sleep pattern). Despite these benefits, the time required to complete the diary and the duration of diary recording pose a time burden for the respondent (Richardson, 1994). This burden of recording is particularly relevant to mothers of infants, thus the challenge in clinical practice or research is to obtain quality information about mother and infant sleep wake pattern while limiting the number of days of recording that are required.
Diaries documenting sleep-wake behavior provide overall information about sleep pattern and timing (bedtime, rise time, sleep duration, number of sleep periods) (Monk et al., 1994). Diary recording may also include contextual information (e.g. bed partner, sleep location, infant co-sleeping, sleep aids, infant feedings) as well as subjective evaluation of sleep quality (e.g. awake feeling refreshed, fatigue score).
The quality of measurement is an important issue, whether an instrument or tool is used for practice or clinical research purposes (Stotts & Aldrich, 2007). Further, evidence-based practice requires attention to how client behaviors and outcomes are measured (Rattray & Jones, 2007) including reliability, the consistency and stability of measurement over time (Stotts et al., 2007). In collecting diary information, the goal is the best portrayal of infant and mother sleep-wake pattern while imposing the fewest number of days of recording. Maternal and infant sleep varies from one day to the next. A diary recorded for only one day may not be an accurate picture of typical sleep-wake pattern. Collecting information for more than one day is desired, but how many days are needed? In both adults and infants, sleep diaries are valid measures (Monk et al., 1994; Rogers, Caruso, & Aldrich, 1993). Although sleep of mothers and infants is an interactive process, there are limited studies that simultaneously examine sleep in the mother-infant pair using home-based diary recordings and there is little empirical evidence about necessary duration of data collection. This study was therefore conducted to determine the minimum duration of data collection for mother-infant sleep diaries.
Study Design and Methods
Design and Sample
Twenty mothers and their four to ten week-old infants participated in the project which involved four day’s of continuous data collection conducted in the participants’ homes. The study was focused on early infancy when major changes in sleep pattern occur and when sleep issues for mothers are prevalent. The four day recording was chosen as a reasonable time period for this initial study defining duration. Non-conclusive results would provide rationale for extending recording time. Inclusion criteria were healthy adult mothers and singleton, term gestation infants experiencing no complications during pregnancy or following birth. Subjects were recruited through web-based advertisement, flyers posted in clinic settings, and postpartum classes. Mothers’ age ranged from 18 to 40 years. The 13 male (65%) and 7 female (35%) infants were between 34 and 74 days postnatal age, mean (SD) = 58.7 (10.6). Seventeen (85%) of the infants were exclusively breastfed. The sample as a whole was comprised of 10 Asian, 2 Black, and 28 white individuals.
Instruments
Mothers recorded their sleep-wake periods as well as their infants’ sleep-wake and feeding periods using a daily diary divided into 15 minute time blocks. Mothers were instructed in the use of alphabetical codes (A – awake, S = sleep, C = cry, F = feeding) used to record both their infant’s and their sleep-wake codes for each 15 minute block of time. During uninterrupted maternal sleep periods when the infant apparently remained asleep, mothers coded the infant as asleep. The diary was adapted from the Sleep-Activity Record developed by Barnard (Barnard, 1999). The accuracy of parent diaries in terms of schedule-related events, such as sleep-onset and duration, has been demonstrated (Sadeh, Hauri, Kripke, & Lavie, 1995).
Procedures
The study was approved by the institutional human subjects review board and written consent was obtained from participating mothers. Subjects were recruited through public advertisement and were visited in the home at the beginning and end of the four day recording period. Demographic and health information were obtained by interview at initiation of the study. A small, battery operated digital clock was mounted on a clip board which secured the diary forms. At study completion diary forms were reviewed with mothers to assure completeness of data entry.
Analysis
Diary data were entered, aggregated by day for each subject pair, and the following summaries were derived: total sleep time, number of sleep periods, longest and mean sleep periods, total cry time, number of cry periods, longest and mean cry period, total feeding time, number of feeding periods, and mean feeding period. Using ANOVA-RM, the data for Day 1 was compared with serial aggregations of Days 1–2, Days 1–3, and Days 1–4 to examine the effect of increasing duration of data collection on average values for the study variables. Additionally study variables calculated using Days 1–4 of data were correlated with values obtained from serial increments in duration of data collection (i.e., Days 1–4 correlated with Days 1–3, Days 1–2, and Day 1). With N = 20 and α = .01, power was 0.98 to detect r ≥ 0.80. These correlations illustrate the effect of increasing duration of data collection on stability.
Results
Infant and mother sleep and activity, measured by diary, varied across subjects suggesting individual differences. There were no statistically significant differences in any of the mother and infant sleep and activity variable means when compared by day. This comparison of separate days demonstrated relative consistency of total sleep, sleep periods, and mean and longest sleep period within mother-infant pairs. Further, infant feeding and cry patterns appeared relatively stable across the four day data collection.
To assess the effect of data collection duration the means of mother and infant sleep and activity variables were compared using incremental increases in number of days of diary data (Table 1). The comparison of Day 1 with Days 1–2, 1–3, and 1–4 did not reveal any statistically significant differences in mean values. Increasing duration of diary data collection incrementally from one to four days did not alter or improve the variable means. The effect of duration of diary data collection on stability was examined by correlating mother and infant sleep and activity variable means calculated using all four days of data with values obtained by using three, two, and one day of data (Table 2). Acceptable level of stability reliability was defined as r ≥ 0.80. Based on this criterion, five sleep and activity measures were adequately represented by one day of data. Thirteen of the sixteen measures were captured by two days of data, the exceptions being longest and mean cry period, and longest feeding period. Correlations between values derived from three vs. four days of data were very high (r = 0.875 to 0.990) indicating three days of diary data provided stable estimates of mother and infant sleep and activity.
Table 1.
Comparison of sleep and activity variable means (SD) calculated using serial increments in duration of mother and infant diary data collection (N = 20).
| Days of Data | ||||
|---|---|---|---|---|
| 1 to 4 | 1 to 3 | 1 to 2 | 1 | |
| Infant | ||||
| Sleep periods/day | 8.8 (1.6) | 8.9 (1.7) | 8.9 (1.9) | 8.7 (2.2) |
| Longest sleep period (min) | 287.4 (75.2) | 283.0 (76.3) | 277.9 (81.4) | 265.5 (84.2) |
| Mean sleep period mean (min) | 96.1 (17.1) | 95.6 (18.3) | 95.1 (19.0) | 94.2 (20.6) |
| Total sleep (min) | 805.2 (78.9) | 802.3 (76.6) | 810.8 (82.1) | 787.5 (101.3) |
| Cry periods/day | 2.1 (2.1) | 2.2 (2.1) | 2.4 (2.4) | 2.4 (2.6) |
| Longest cry period (min) | 22.0 (23.0) | 21.3 (26.0) | 17.3 (17.4) | 18.0 (18.6) |
| Mean cry period (min) | 17.4 (19.3) | 16.8 (22.1) | 12.0 (9.2) | 12.3 (9.2) |
| Total cry (min) | 46.6 (51.4) | 47.0 (53.4) | 45.4 (48.6) | 45.0 (52.9) |
| Feeding periods/day | 9.7 (2.5) | 9.9 (2.5) | 10.0 (2.6) | 10.5 (3.2) |
| Longest feeding period (min) | 39.4 (15.6) | 39.5 (15.3) | 37.1 (13.9) | 36.8 (12.4) |
| Mean feeding period (min) | 24.3 (7.1) | 24.5 (7.5) | 24.1 (7.6) | 23.6 (7.1) |
| Total feeding (min) | 229.1 (79.4) | 232.3 (82.2) | 230.3 (73.9) | 234.8 (71.4) |
| Mother | ||||
| Sleep periods/day | 3.4 (1.0) | 3.3 (.9) | 3.4 (.9) | 3.5 (1.4) |
| Longest sleep period (min) | 237.3 (88.1) | 238.0 (86.3) | 229.5 (87.0) | 224.3 (99.4) |
| Mean sleep period (min) | 145.5 (55.3) | 151.3 (59.6) | 143.1 (52.4) | 137.7 (59.7) |
| Total sleep (min) | 418.2 (65.8) | 421.3 (68.7) | 423.4 (68.5) | 418.5 (84.6) |
NOTE: ANOVA-RM, p > 0.05 for all comparisons
Table 2.
Day 1 to 4 sleep and activity variable means correlated with means calculated from incremental durations of mother and infant diary collection (N = 20).
| Days | |||
|---|---|---|---|
| 1–3 | 1–2 | 1 | |
| Infant | |||
| Sleep periods | 0.956 | 0.909 | 0.731 |
| Longest sleep period | 0.970 | 0.878 | 0.890 |
| Mean sleep period | 0.889 | 0.834 | 0.752 |
| Total sleep | 0.966 | 0.860 | 0.677 |
| Cry periods | 0.990 | 0.938 | 0.749 |
| Longest cry period | 0.986 | 0.715 | 0.538 |
| Mean cry period | 0.989 | 0.546 | 0.329 |
| Total cry | 0.989 | 0.915 | 0.709 |
| Feeding periods | 0.982 | 0.944 | 0.882 |
| Longest feeding period | 0.963 | 0.708 | 0.712 |
| Mean feeding period | 0.987 | 0.946 | 0.908 |
| Total feeding | 0.984 | 0.959 | 0.851 |
| Mother | |||
| Sleep periods | 0.875 | 0.800 | 0.656 |
| Longest sleep period | 0.975 | 0.887 | 0.850 |
| Mean sleep period | 0.985 | 0.842 | 0.746 |
| Total sleep | 0.963 | 0.860 | 0.643 |
Note: shaded areas = r < 0.80
Clinical Implications
Reliability testing indicated that three days of diary data were required to achieve stability of all measures. Results therefore suggest that a three day data collection period is sufficient for diary recording of mother and infant sleep using the tested diary instrument. If crying and longest feeding period are not measures of interest, two days of data collection could be justified. Findings of the study are limited to similar diaries using 15 minute recording intervals. Further investigations should expand evaluation of mother and infant sleep-wake diaries to a broader range of infant ages as well as test for possible ethnic and racial effects.
Mother-infant sleep diaries provide valuable information relevant to practice that can be used to assess adequacy of maternal and infant sleep, diagnose sleep related problems (infrequent infant feeding, short intra-feeding interval, maternal sleep fragmentation and inadequate total sleep). Interventions, based on diary findings, may include assisting the mother to organize infant caregiving, identifying opportunities for maternal naps, or improving feeding practices. Diaries collected over time are also useful for anticipatory guidance and teaching mothers about their infant’s sleep development.
In conclusion, for the mothers and their infants studied, three days of diary collection produced reliable measurement of sleep-wake pattern. Longer recording periods increase demands placed on mothers while shorter periods may not adequately cover day-to-day variation.
Box – Clinical Implications.
Diaries are useful tools for assessing sleep-wake pattern in the nursing care of mothers and infants.
Nursing assessment measures should provide clinically relevant as well as reliable data.
The needed duration of mother-infant sleep-wake diary collection should be based on evidence.
The structured diary tested in this study provided reliable data when collected over a three day period.
Acknowledgements
Funded by National Institute of Nursing Research RO3 NR009038
Footnotes
The authors have no conflict of interest to disclose.
CALLOUTS
Infant sleep is one of the most common health problems reported by mothers and a structured diary is an inexpensive and easy means of assessing mother and infant sleep-wake pattern.
Mother-infant sleep-wake diaries can provide important clinical information about sleep timing and duration, feeding frequency, and crying periods.
Although direct measurement of maternal and infant sleep supports nursing assessment of sleep problems, there is little evidence indicating the appropriate number of days of diary recording to assure reliable measurement of mother and infant sleep-wake behaviors.
While collecting diary data over more than one day improved measurement of mother and infant sleep and feeding, three days of data were sufficient to reliably determine sleep-wake pattern.
For the type of diary tested, a three day recording period is recommended to reliably assess maternal and infant sleep-wake pattern.
- Mom’s Sleep Test, National Sleep Foundation http://www.sleepfoundation.org/site/c.huIXKjM0IxF/b.2698511/k.8F23/Moms_Sleep_Test.htm (last accessed 7/9/2008)
- Children and Sleep, National Sleep Foundation http://www.sleepfoundation.org/site/c.huIXKjM0IxF/b.2418873/k.B9AD/Children_and_Sleep.htm (last accessed 7/9/2008)
- Lee, Kathryn A. & Ward, Teresa M. (2005). Critical Components of a sleep assessment for clinical practice settings. Issues in Mental Health Nursing, 26 (7), 739–750. Retrieved July 09, 2008, from http://www.informaworld.com/10.1080/01612840591008320
Contributor Information
Karen A. Thomas, Email: kthomas@u.washington.edu, Department of Family and Child Nursing, University of Washington, Seattle, WA.
Robert L. Burr, Email: bobburr@u.washington.edu, Department of Biobehavioral Nursing and Health Systems, University of Washington, Seattle, WA.
Reference List
- Barnard KE. Beginning rhythms: the emerging process of sleep wake behavior and self-regulation. Seattle, WA: NCAST, University of Washington; 1999. [Google Scholar]
- Darlington AS, Wright CM. The influence of temperament on weight gain in early infancy. Journal of Developmental and Behavioral Pediatrics. 2006;27:329–335. doi: 10.1097/00004703-200608000-00008. [DOI] [PubMed] [Google Scholar]
- Feldman R. From biological rhythms to social rhythms: Physiological precursors of mother-infant synchrony. Developmental Psychology. 2006;42:175–188. doi: 10.1037/0012-1649.42.1.175. [DOI] [PubMed] [Google Scholar]
- Lam P, Hiscock H, Wake M. Outcomes of infant sleep problems: a longitudinal study of sleep, behavior, and maternal well-being. Pediatrics. 2003;111:e203–e207. doi: 10.1542/peds.111.3.e203. [DOI] [PubMed] [Google Scholar]
- Lee KA, Ward TM. Critical components of a sleep assessment for clinical practice settings. Issues in Mental Health Nursing. 2005;26:739–750. doi: 10.1080/01612840591008320. [DOI] [PubMed] [Google Scholar]
- Monk TH, Reynolds CF, Kupfer DJ, Buysse DJ, Coble PA, Hayes AJ, et al. The Pittsburgh Sleep Diary. Journal of Sleep Research. 1994;3:111–120. [PubMed] [Google Scholar]
- Nishihara K, Horiuchi S, Eto H, Uchida S. The development of infants' circadian rest-activity rhythm and mothers' rhythm. Physiology and Behavior. 2002;77:91–98. doi: 10.1016/s0031-9384(02)00846-6. [DOI] [PubMed] [Google Scholar]
- Rattray J, Jones MC. Essential elements of questionnaire design and development. Journal of Clinical Nursing. 2007;16:234–243. doi: 10.1111/j.1365-2702.2006.01573.x. [DOI] [PubMed] [Google Scholar]
- Richardson A. The health diary: an examination of its use as a data collection method. Journal of Advanced Nursing. 1994;19:782–791. doi: 10.1111/j.1365-2648.1994.tb01151.x. [DOI] [PubMed] [Google Scholar]
- Rogers AE, Caruso CC, Aldrich MS. Reliability of sleep diaries for assessment of sleep/wake patterns. Nursing Research. 1993;42:368–372. [PubMed] [Google Scholar]
- Sadeh A, Hauri PJ, Kripke DF, Lavie P. The role of actigraphy in the evaluation of sleep disorders. Sleep. 1995;18:288–302. doi: 10.1093/sleep/18.4.288. [DOI] [PubMed] [Google Scholar]
- Stotts NA, Aldrich KM. How to try this: define your terms. Evaluating instruments for use in nursing practice. American Journal of Nursing. 2007;107:71–72. doi: 10.1097/01.NAJ.0000292209.82807.20. [DOI] [PubMed] [Google Scholar]
- Symon BG, Marley JE, Martin AJ, Norman ER. Effect of a consultation teaching behaviour modification on sleep performance in infants: a randomised controlled trial. Medical Journal of Australia. 2005;182:215–218. doi: 10.5694/j.1326-5377.2005.tb06669.x. [DOI] [PubMed] [Google Scholar]
- Thomas KA, Wang S. Infant sleep and feeding pattern: Effects on maternal sleep. Journal of Midwifery & Women's Health. 2005;50:399–404. doi: 10.1016/j.jmwh.2005.04.010. [DOI] [PubMed] [Google Scholar]
- Wulff K, Wulff W, Siegmund R. Circadian patterns of rest/activity in infants and their mothers: chronobiological aspects of social synchronization. Journal of Sleep Research. 2002;11:253–254. [Google Scholar]