Adverse Childhood Experiences (ACEs) are experiences of a traumatic nature to which persons are exposed before the age of 18 years. Increasing evidence shows that ACEs are associated with numerous adverse health outcomes in adulthood [1]. In one study, ACEs were found to be associated with a two-fold higher odds of anxiety disorders, internalizing disorders, depression, and suicidality [2]. These associations did not significantly vary by gender or the age of exposure. In other studies, persons exposed to multiple ACEs had an increased risk of asthma onset by 31% compared to those exposed to ≤ 1 ACE [3], a 70–100% increased risk for hospitalization with rheumatic diseases and other autoimmune diseases [4], increased anger expression and perceived stress [5], and elevated psychological distress, reduced emotional wellbeing, autonomic dysregulation, alterations in nocturnal heart rate and heart rate variability [6].

Exposure to ACEs has also been found to affect sleep quality and quantity in adulthood. Among 863 U.S. adults (25–76 years) who participated in the Biomarker Project in the Midlife in the United States Refresher study, experiencing more adverse events or adverse events in both childhood and adolescence was associated with worse self-reported sleep and actigraphic sleep, including longer sleep-onset latency, lower sleep efficiency, and longer wake after sleep onset (WASO) [7]. Data from the 2011 Behavioral Risk Factor Surveillance System showed that adults with three or more ACEs were over twice as likely to report short (<6 h/night) versus optimum sleep duration than those with no ACEs [8].

High quality and an adequate quantity of sleep are critical elements for optimum performance and good health [9]. There is abundant evidence showing that inadequate and poor sleep is associated with serious health conditions. Grandner (2017) describes several of these conditions in a review article [10]. The conditions include increased mortality risk [11], increased weight gain [12,13], risk of diabetes [14,15], higher levels of systemic inflammation [16,17], increased risk of cardiovascular disease [18], cognitive problems [19], mental health problems [20], and increased risk of suicide [21].

Americans do not get enough sleep. A study conducted among 444,306 adults in all 50 states and the District of Columbia found that 65.2% of respondents reported a healthy sleep duration (≥7 h/24-h period) [22]. The age-adjusted prevalence of ≥ 7 h of sleep in a 24-h period was lower among non-Hispanic blacks, American Indians/Alaska Natives, Native Hawaiians/Pacific Islanders, and multiracial respondents, compared with non-Hispanic whites, Hispanics, and Asians. Insufficient sleep affects several aspects of professional and personal life. In the National Sleep Foundation’s 2020 Sleep in America poll, 40% of adults say feeling sleepy at least occasionally interferes with their daily activities [23].

Adequate and good quality sleep is beneficial to persons in all professions but may be most critical for workers whose jobs involve life and death decisions such as air traffic controllers, health care professionals, and the various first responders. To the best of our knowledge there have been no published studies investigating associations between ACEs and sleep quantity or quality among police officers. The objective of this study was to investigate associations of ACEs with self-reported sleep duration and several objective sleep measures among police officers. We hypothesized that higher ACE scores would be significantly associated with worse sleep measures.

Descriptive statistics for the participants are presented in Table 1. Participants had a mean (±SD) age of 49.4 ± 10.0 years, 29.1% were female, 81.6% were White/Hispanic, and 49.0% were patrol officers. The mean ACE score for all participants was 1.5 ± 1.8 (range = 0–8) and women had a significantly higher mean ACE score than men (2.1 ± 2.2 vs. 1.3 ± 1.5; p = 0.007). Thirty-eight percent reported that they experienced no ACEs, 24.3% reported 1 ACE, 24.8% reported 2–3 ACEs, and 12.6% reported ≥ 4 ACEs. Women reported higher frequencies of two or more ACEs compared to men (48.4% vs. 32.9%; p = 0.037). ACE score was positively correlated with depressive symptoms (correlation coefficient = 0.331, p < 0.0001) and perceived stress score (0.283, p < 0.0001) (data not shown).

Mean self-reported sleep duration was 6.2 ± 1.3 h while mean sleep duration as measured by actigraphy was 6.6 ± 1.0 h (Table 1). Several measures of objective sleep were significantly different between the sexes. Objective sleep duration was significantly higher in women compared to men (6.9 ± 0.89 vs. 6.5 ± 1.1 h; p = 0.004). Compared to men, women fared better with a lower mean activity index (30.0 ± 8.7 vs. 36.6 ± 11.6; <0.0001), a lower mean number of wake episodes (9.7 ± 4.1 vs. 11.4 ± 4.7; 0.017), a lower mean sleep fragmentation index (3.1 ± 1.2 vs. 3.8 ± 1.6; <0.001), and a lower mean number of sleep episodes (11.4 ± 4.3 vs. 13.1 ± 4.9; p = 0.019).

Table 2 presents prevalence of ACEs. The prevalence of positive responses to the questions (ie, adverse experiences) varied considerably across the 10 items ranging from 1% (item #5) to 38% (item #6). Compared to men, higher percentages of women answered ‘yes’ to nine of the ten ACE questions and for six of those questions (items # 3, 4, 7, 8, 9, 10) the prevalence in women was significantly higher than in men. A significantly higher percentage of women reported childhood sexual abuse compared to men (15.0% vs. 2.7%; p = 0.002). Compared to men, a higher percentage of women reported feeling unloved (18.3% vs. 6.2%; p = 0.007); experiencing childhood physical abuse (16.7% vs. 6.2%; p = 0.018); parental drug use (25.0% vs. 18.5%; p = 0.029); parental mental illness (26.7% vs. 12.3%; p = 0.012); and parental incarceration (11.7% vs. 2.7%; p = 0.016).

Table 3 shows associations of ACEs with self-reported sleep duration and objective measures of sleep from actigraphy among all participants. The mean self-reported sleep duration was significantly lower among participants who reported ≥1 ACEs compared to those who reported no ACEs (6.0 ± 0.11 vs. 6.4 ± 0.14 h; multivariate-adjusted p = 0.035). Objective sleep duration was not significantly associated with ACEs. Sleep efficiency was significantly better among participants who reported no ACEs (mean = 90.2%, 95% CI = 89.2–91.2) compared to those who reported ≥ 1 ACEs (88.7%, 87.7–89.6; unadjusted p = 0.031). These associations remained statistically significant after adjusting for age but was slightly attenuated after further adjustment for hypertension, triglycerides, BMI, waist circumference, depressive symptoms, perceived stress, and workload (90.1%, 88.9–91.1 vs. 88.8%, 87.8–89.7; p = 0.094).

Participants who reported ≥1 ACEs had a higher mean activity index score (mean = 36.0 ± 11.9) compared to those who reported no ACEs (32.5 ± 9.7); p = 0.028 (Table 3). After full adjustment for confounders, the difference in the mean values between the two ACE groups was even more pronounced (0 ACE = 31.2 ± 1.25 vs. ≥1 ACEs = 36.9 ± 0.96; p = 0.001). We also found significant associations between ACEs and WASO. In the fully adjusted model, participants who reported ≥ 1 ACEs had a higher mean WASO of 44.3 ± 2.24 min whereas those who reported no ACEs had a mean WASO of 35.3 ± 2.92 min; p = 0.019. Sleep fragmentation index was significantly higher among participants who reported ≥1 ACEs compared to those who reported none before adjustment (p = 0.044) and just slightly attenuated after multivariate adjustment (3.8 ± 0.13 vs. 3.3 ± 0.18; p = 0.062). None of the other sleep measures (ie, sleep onset latency, latency to persistent sleep, number of wake episodes, and number of sleep episodes) was significantly associated with ACEs.

The sex-stratified results showed a few differences in the associations between ACEs and sleep measures among women and men (Table 4). The mean self-reported sleep duration was significantly lower among men (but not among women) who reported ≥ 1 ACEs compared to those who reported no ACEs (multivariate model: 5.9 ± 0.13 vs. 6.4 ± 0.15 h; p = 0.025). Men who reported ≥ 1 ACEs showed a lower mean sleep efficiency score compared to those who report no ACEs (age-adjusted model: 88.0%, 86.7–89.2 vs. 89.9%, 88.6–91.1; p 0.038). This association was attenuated after multivariate adjustment (88.4%, 87.1–89.5 vs. 89.4%, 87.9–90.7; p 0.293). Also, men who reported ≥ 1 ACEs showed a significantly higher mean activity index compared to those who report no ACEs (multivariate adjusted: 39.1 ± 1.3 vs. 33.2 ± 1.51; p = 0.004). After adjustment for age but not in the multivariate-adjusted models, men who reported ≥ 1 ACEs showed a higher mean WASO (46.6 ± 2.9 vs. 36.1 ± 3.4; p = 0.020) and a higher mean sleep fragmentation index (4.1 ± 0.17 vs. 3.5 ± 0.20; p = 0.021) compared to those who reported no ACEs. Both associations were slightly attenuated after multivariate adjustment. None of the associations between ACEs and sleep measures were statistically significant among women. Sex, race/ethnicity, and social support did not significantly modify the relationship between ACEs and any of the sleep measures.

Table 5 shows associations between selected questions of ACEs (rather than the total ACE score) and the sleep measures that showed significant relationships among all participants in Table 3. Compared to participants who did not report experiencing these events, participants were found to have a shorter mean sleep duration if they reported yes to question #1 (Did a parent or other adult in the household often or very often swear at you, insult you, put you down, or humiliate you? Or act in a way that made you afraid that you might be physically hurt?) (6.3 ± 0.15 vs. 6.7 ± 0.08 h; multivariate adjusted p = 0.047) and to question #2 (Did a parent or other adult in the household often or very often push, grab, slap, or throw something at you? Or ever hit you so hard that you had marks or were injured?) (6.2 ± 0.15 vs. 6.7 ± 0.08 h; multivariate adjusted p = 0.007).

Three objective sleep measures showed significant associations with Question #8 (Did you live with anyone who was a problem drinker or alcoholic or used street drugs?) (Table 5). Compared to those who did not report experiencing this exposure, participants who reported yes to question #8 had a lower (ie, worse) mean sleep efficiency (87.6, 85.7–89.2 vs. 89.7, 88.9–90.4; multivariate adjusted p = 0.026). None of the other individual questions was significantly associated with sleep efficiency. Participants who reported yes to question #8 also had a higher (ie, worse) mean activity index (37.7 ± 1.7 vs. 34.0 ± 0.85; multivariate adjusted p = 0.049) and a higher (ie, worse) mean number of minutes of WASO (50.2 ± 3.9 vs. 38.4 ± 1.9 min; multivariate adjusted p = 0.008) compared to those who did not report experiencing this exposure.

In this study, we sought to investigate cross-sectional associations between ACEs and several measures of sleep quantity and quality among police officers. Our results showed that participants who were exposed to ≥1 ACEs had significantly shorter self-reported sleep duration compared to those who reported no ACE exposure. Interestingly, this association was not significant when sleep duration was assessed by actigraphy. Results also showed that, compared to no ACE exposure, exposure to ≥1 ACEs was significantly associated with, on average, a lower sleep efficiency, a higher activity index score, and a higher number of wakes after sleep onset. ACEs were not significantly associated with any of the other sleep measures (ie, sleep onset latency, latency to persistent sleep, number of wake episodes, sleep fragmentation index, and by sex, significant associations were observed between a few ACEs and sleep measures, but only among men. Compared to male participants who reported no ACE exposure, men who reported past exposure to ≥1 ACEs had, on average, a shorter self-reported sleep duration, a lower sleep efficiency, a significantly higher activity index, a higher number of wakes after sleep onset, and a higher sleep fragmentation index. No significant associations were observed between ACEs and sleep measures among women.

The findings of this current study are consistent with those of several studies even though the participants, sample sizes, length of the ACE questionnaire, and other factors may have differed. In a systematic review article, approximately 90% of the retrospective studies reported statistically significant associations between various sleep disorders among persons with a history of childhood adversity [31]. In many of these studies, the strength of associations increased with the number and severity of adverse experiences. In a study investigating persons in a low-income community, persons who had experienced ACEs were more likely to have heightened stress levels and sleep disturbances compared to those who had not experienced ACEs [32].

In another study, 9.8% of 8184 participants reported childhood sexual abuse and childhood sexual abuse significantly predicted insomnia symptoms among women decades after abuse [33]. The authors also found that exposure to more than one perpetrator and feeling forced/threatened increased sleep risk. Sheehan and colleagues (2020) investigated associations of the quantity, timing, and type of childhood adversity with subjective and actigraphic sleep measures among 863 U.S. adults (25–76 years) who had participated in the Biomarker Project in the Midlife in the United States Refresher study [7]. This study included several distinct types of adverse childhood events. The authors observed that childhood adversity was related to worse subjective and actigraphic sleep measures (except for total sleep duration) after controlling for age, sex, and race. Exposure to more adverse events, particularly three or more events, or adverse events during both childhood and adolescence, was associated with worse self-reported sleep and actigraphic sleep, including longer sleep-onset latency, sleep efficiency, and longer WASO. A study conducted on 22,403 adults using data from the 2011 Behavioral Risk Factor Surveillance System found that short sleep duration (<6 h/night) was positively and significantly associated with the number of ACEs [8]. Each individual adverse experience was associated with higher odds of short sleep duration, with physical abuse (ie, parents hitting each other, parents hitting children, and rape) having the strongest likelihood. This association was observed for each decade of age until the 60s, although the magnitude attenuated with age. Baiden and colleagues (2015) examined the association between early childhood adversities and troubled sleep among 19,349 adult Canadians using the Canadian Community Health Survey – Mental Health (CCHS-MH) [34]. For each additional childhood adversity experienced, the odds of having sleep problems such as insomnia or disordered breathing while sleep increased by 10% after controlling for sociodemographic, socioeconomic, health, and mental health factors. These results also revealed that more severe and chronic types of childhood adversities, such as sexual, physical, and multiple types of abuse, had the largest associations with sleep problems.

In the current study, investigation of the individual ACE questions revealed that positive responses to Question #8 (Did you live with anyone who was a problem drinker or alcoholic or used street drugs?) was associated with reduced sleep continuity. Exposure to this ACE event was associated with, on average, a lower sleep efficiency, a higher activity index, and a higher WASO. Positive responses to both ACE questions #1 (Did a parent or other adult in the household often or very often swear at you, insult you, put you down, or humiliate you? Or act in a way that made you afraid that you might be physically hurt?) and #2 (Did a parent or other adult in the household often or very often push, grab, slap, or throw something at you? Or ever hit you so hard that you had marks or were injured?) were significantly associated with shorter self-reported sleep duration. Other ACE questions were not associated with sleep measures. Questions on childhood neglect (question #4), poverty (#5), divorce (#6), parental mental illness (#9), and parental incarceration (#10) were not observed to be significantly associated with shorter sleep duration, sleep efficiency, activity index, or WASO. Although some of these findings may have resulted from reduced statistical power, other factors which are not entirely clear may also be responsible. This is a topic that warrants future investigation.

The associations observed between ACEs and sleep measures may occur through several mechanisms. These individuals who are exposed to ACEs may be exposed to other adverse events inside or outside their homes, may adopt poor strategies to deal with their trauma that exacerbate their already vulnerable conditions, or may become hyper-aroused when confronted with acute stressors in adulthood [35]. Any one or a combination of these and other factors can also negatively affect sleep quality.

Data from the National Sleep Foundation’s 2020 Sleep in America poll show that poor sleep can impact mood (58%), cause occasional irritability (55%), headaches (36%), and a general feeling of being unwell (33%) [23]. For participants who might be experiencing sleep disorders, there are strategies that can be adopted to mitigate these problems. Social support from family and friends has been shown to decrease trauma symptoms among both women and men [36,37]. Other strategies that are increasingly commonly used and found to be effective are emotional freedom technique (also known as tapping) [38], mindfulness meditation [39,40], and improved sleep hygiene [41].

Results of this study showed that exposure to ACEs are associated with shorter sleep duration and worse sleep quality during adulthood among police officers. These results may be underestimated. Although a significant difference in sleep efficiency was observed between those who experienced ACEs and those who did not, the mean sleep efficiency in both groups was above what is considered “normal” (>85%) and hence caution is advised when interpreting the result.

Police officers have demanding duties which can be very stressful even when they have good quality and sufficient hours of sleep. Having less than optimum sleep increases the chances of officers not performing to the best of their ability which can increase the chances of making mistakes on the job, some of which can be fatal. Future research, which includes using a more comprehensive ACE questionnaire, collection of adverse events and lifestyle habits during adulthood, and a larger sample size, is warranted.