The Military Service Sleep Assessment: an instrument to assess factors precipitating sleep disturbances in U.S. military personnel

Abstract

Study Objectives:

Military personnel frequently experience sleep difficulties, but little is known regarding which military or life events most impact their sleep. The Military Service Sleep Assessment (MSSA) was developed to assess the impact of initial military training, first duty assignment, permanent change of station, deployments, redeployments, and stressful life events on sleep. This study presents an initial psychometric evaluation of the MSSA and descriptive data in a cohort of service members.

Methods:

The MSSA was administered to 194 service members in a military sleep disorders clinic as part of a larger study.

Results:

Average sleep quality on the MSSA was 2.14 (on a Likert scale, with 1 indicating low and 5 indicating high sleep quality), and 72.7% (n = 140) of participants rated their sleep quality as low to low average. The events most reported to negatively impact sleep were stressful life events (41.8%), followed by deployments (40.6%). Military leadership position (24.7%) and birth/adoption of a child (9.7%) were the most frequently reported stressful life events to negatively impact sleep. There were no significant differences in current sleep quality among service members with a history of deployment compared with service members who had not deployed.

Conclusions:

The MSSA is the first military-specific sleep questionnaire. This instrument provides insights into the events during a service member’s career, beyond deployments, which precipitate and perpetuate sleep disturbances and likely chronic sleep disorders. Further evaluation of the MSSA in nontreatment-seeking military populations and veterans is required.

Citation:

Mysliwiec V, Pruiksma KE, Brock MS, et al. The Military Service Sleep Assessment: an instrument to assess factors precipitating sleep disturbances in U.S. military personnel. J Clin Sleep Med. 2021;17(7):1401–1409.

BRIEF SUMMARY

Current Knowledge/Study Rationale: Service members have high rates of sleep disturbances. The Military Service Sleep Assessment was designed to increase an understanding of why this otherwise healthy population develops sleep disturbances and chronic sleep disorders at such a high rate.

Study Impact: Although previous studies have investigated specific events in a military career, this novel instrument provides a comprehensive assessment of the military and life events that can cause sleep disturbances in service members. The initial findings from the MSSA suggest that stressful life events and deployments most negatively impact sleep quality, and for many service members there are multiple events that perpetuate their sleep disturbances; these findings could result in targeted interventions for sleep disturbances related to specific events in service members.

INTRODUCTION

Military personnel have high rates of sleep disturbances, with nearly 50% reporting poor sleep quality.¹ The most frequently reported sleep disturbances are short sleep duration² and insomnia symptoms.³ These general or nonspecific sleep disturbances are distinct from but likely contribute to the development of insomnia and circadian rhythm sleep-wake disorders (eg, shift work disorder). Although the conventional wisdom is that deployment is the primary causal factor for sleep disturbances in military personnel,^4–6 it is recognized that military service in general is associated with disturbed sleep. For example, Seelig, Jacobson, Smith, et al⁶ reported that deployment, combat exposure, and increased stress were all associated with decreased sleep quantity and quality; however, the study found that there was only a 0.1-hour difference in sleep duration between military personnel who had deployed and those who had not. Thus, there are likely military-related factors or events other than a deployment that contribute to sleep disturbances.⁷

To address the marked increase in sleep disorders in military personnel,^1,8 a better understanding is needed of the particular military or life events that occur during military service that are associated with decreased sleep quality. There are many aspects of military service that can serve as precipitating factors for poor-quality sleep.⁹ Understandably, deployment is the most recognized factor.⁴ The depiction of service members in austere environments engaged in combat is an easily understood cause of sleep problems.^4,5,8 Yet sleep can be negatively impacted during other military events during a service member’s career, such as initial military training,¹⁰ permanent change of station (PCS), the period immediately before deployment,¹¹ and return from deployment (ie, redeployment).²

Little is known regarding which military and life events have the greatest negative impact on sleep quality, or even how sleep quality changes throughout a military career.¹² Attributing poor sleep solely to deployments, which is the current approach, runs the risk of not addressing other potentially modifiable military-related factors. Here we briefly review the major military and life events that typically occur during a service member’s career and are likely to impact sleep quality.

Initial military training

Initial basic military training varies among branches, but it is considered to be physically and mentally demanding regardless of the branch of service. During initial military training, a service member’s day usually begins early and ends late. Many military recruits are in their late teens or early twenties, which is the time when average circadian rhythms are slightly delayed. This is inconsistent with the early awakening schedule required during military training^13,14 and may contribute to decreased sleep quality. Furthermore, sleep during initial training may be negatively impacted by noise, evening work details, hunger, and other stress.¹⁵ This may also be the first time that the service member has been away from home for an extended period, which is also a significant stressor.

PCS

Many service members are required to undergo a PCS (ie, a military-required move), both domestically and internationally, to meet global force requirements, and these events are known to be a significant stressor for service members.^16,17 These relocations may require family separation or result in the loss of social support, which alters family life habits and structure. Furthermore, the logistics of moving can be emotionally and physically draining¹⁸ and can increase financial stress, especially if a spouse has to look for new employment. All of these aspects of a PCS can negatively impact sleep.^19,20

Deployment

The impact of deployment on sleep varies depending on the nature of the deployment; still, the exposure to austere environments, traumatic experiences, and insufficient sleep are the primary reasons that deployments negatively impact sleep quality.²¹ Some deployments are combat-related (eg, to Iraq and Afghanistan) whereas other deployments do not necessarily involve combat (eg, to Kuwait or Qatar). In the contemporary operating environment, service members are deployed to approximately 177 countries for peacekeeping missions, defense support of civil authorities, training in other environments, or joint/“host-nation” training opportunities.²² Depending on the deployed location, service members may face jet lag or circadian misalignment from transcontinental flights or staying up to communicate with family and friends. In these environments, sleeping conditions are often suboptimal because of uncomfortable bedding, insects, extreme temperatures, or ambient noises.⁵ During combat deployments, service members may experience poor-quality sleep because of safety threats, including exposure to small-arms fire, mortar, or rocket attacks during their sleep period; prolonged operations with little or no time to sleep; or nighttime missions, which are not conducive to healthy sleep.^4,5 Although noncombat deployments involve different challenges from combat deployments, aspects such as prolonged workdays, non-24-hour duty cycles, and suboptimal sleeping environments negatively impact sleep.²³

Redeployment

Service members can experience disrupted sleep upon returning from deployment because of jet lag, excitement, changes in family dynamics²⁴ lack of support at work, or recovery from both physically and psychologically traumatic deployment-related experiences.^3,25 They may experience difficulties reintegrating into their family or adjusting to a sleeping environment where it is no longer necessary to “sleep with one eye open” to react to danger. Supporting this assertion, a cross-sectional study of 3,152 U.S. Army soldiers surveyed 90–180 days after completing a combat deployment to Iraq found that 72% slept ≤ 6 hours per night,² substantiating that sleep disturbances persist in this time period.

Stressful life events

Stressful life events are known to be a leading precipitant of insomnia in civilians.²⁰ Military personnel can experience similar stressful life events during their career that can negatively impact sleep quality, but this situation has not been systematically evaluated. Stressful life events for an active-duty service member can include nonservice-related events, such as pregnancy,²⁶ birth of a child/adoption, infertility and treatment, sexual dysfunction, marriage/divorce,²⁷ child care, financial hardship, and civilian legal issues. Military-related life events not associated with deployments that negatively impact sleep quality include training injury/accident or illness, attendance in military courses, rotating shifts, and assignments requiring short work recall.¹ Traumatic experiences can negatively impact sleep quality in civilians, especially those in hazardous occupations,²⁸ and in military personnel. Exposure to trauma including actual or threatened death, serious injury, sexual violence,²⁹ a serious accident,³⁰ assault, and natural disasters can occur during military service, likely with greater frequency and leading to increased posttraumatic symptom severity compared to that in civilians.^31–33

Military Service Sleep Assessment

The Military Service Sleep Assessment (MSSA) is a questionnaire the authors designed to evaluate sleep quality in service members and the impact of major military and life events that occur at various times during a military career (MSSA Questionnaire ^{(164.1KB, pdf)} in the supplemental material). This questionnaire offers a brief and systematic way of exploring how different aspects of military service impact sleep. The first section of the MSSA measures service members’ sleep quality over the past 3 months, their primary and secondary self-reported sleep problems, and the perception of whether their sleep problems were caused by military service. The second section examines service members’ reports of their sleep quality during initial military training, their first military assignment, PCS, deployments, and redeployments. The third section of the MSSA assesses stressful life events that may have negatively impacted sleep including nonservice-related events, military-related events other than deployment, and traumatic experiences that may have occurred outside of a deployment. The final portion asks service members to rate the top 3 events that most negatively impact their sleep quality.

The current study is the first to utilize the MSSA. Our aims were to report the military and life events that had the most negative impact on sleep quality and examine differences in MSSA responses between service members who had deployed vs those who had not deployed.

METHODS

Participants

The present study surveyed 194 active-duty U.S. service members who were referred to the Sleep Disorders Center at Wilford Hall Ambulatory Surgical Center at Joint Base San Antonio-Lackland in Texas. The participants consented to be part of a larger ongoing observational study entitled “Sleep Disorders in Military Personnel” examining the impact of gender on sleep disorders in active-duty men and women. The 59th Medical Wing Institutional Review Board served as the single institutional review board for this study.

Measures

MSSA

The MSSA was developed for this study. It is a 19-item, self-report measure that retrospectively evaluates sleep quality and the events during a person’s military career that are most likely to negatively impact sleep, as described above. The MSSA is included in the supplemental material. After the authors generated a pool of clinically salient items, the MSSA was reviewed in 5 iterations by individuals with expertise in assessment development. Subsequent modifications to the instrument were made based on the experts’ recommendations until there was a consensus that the measure was ready to be pilot-tested. The study team pilot-tested the MSSA twice, involving research assistants, project coordinators, and 10 veterans. It was subsequently modified for clarity and ease of use. The readability of the measure’s instructions and items were designed to have a Flesch Reading Ease > 60 (63.4) and a Flesch-Kincade Grade Level < 7.0 (7.2), which is an 8th to 9th grade English reading level. The responses regarding stressful life events included a section for service members to describe the 2 event(s) that most negatively impacted their sleep. For this study, these events were adjudicated into separate categories of nonservice-related, military-related other than deployment, or related to a traumatic experience other than deployment by 2 experienced military sleep researchers (VM, KEP). As an initial psychometric evaluation in this sample of military service members, the interitem correlations of the ratings of the top 3 events that negatively impacted sleep (ie, item 19) and the corresponding event Likert rating of sleep quality for that event (ie, items 17 and 18) were evaluated using Cohen’s κ estimates, which can be interpreted as follows: 0.41–0.60 as moderate agreement, 0.61–0.80 as substantial agreement, and 0.81–1.0 as near-perfect agreement.³⁴ Cohen’s agreement was defined as an endorsement of the most impactful event on item 19 corresponding to the event score that was rated as the most impactful event (ie, worst sleep quality according to the Likert scale); for agreement purposes, the most impactful event could also be equally rated with at least 1 of the other events (ie, the event rated as having the greatest negative impact on sleep could have the same Likert score as another event).

There was nearly perfect agreement by conventional standards between the item responses (κ = 0.87; 95% confidence interval ± 0.06; P < .001). In total, there was a 90.1% agreement consistency between the items rated as “most impactful” on item 19 and the corresponding event Likert rating(s) on items 17 and 18. There were, however, variations in the level of agreement across individual events. Response agreement consistency was high on deployment (93.6%), the first life event (98.2%), and the second life event (96.0%); substantial on redeployment (80.0%); and moderate on initial training (53.8%) and PCS (60.0%).

Demographic questionnaire

The demographic questionnaire is a 19-item measure that includes questions related to participants’ race, ethnicity, height, weight, marital status, and highest education level obtained. It also contains questions regarding branch of service, rank, and, if the service members had deployed, duties during deployment and the operations in which they served.³⁵

Pittsburgh Sleep Quality Index

The Pittsburgh Sleep Quality Index (PSQI)³⁶ assesses sleep quality in the month before assessment. It consists of 4 fill-in-the-blank questions assessing sleep patterns and 14 Likert items rated on a 4-point scale assessing different reasons for trouble sleeping. The PSQI has good internal consistency (Cronbach’s α = .83) and test-retest reliability (r = .85).³⁶ Items make up 7 component scores, which are then summed to yield a global sleep quality index. A cutoff score of 5 on the global sleep quality index is utilized to distinguish “good” sleepers from “poor” sleepers with a diagnostic sensitivity of 89.6% and specificity of 86.5%. The global sleep quality index was utilized as a retrospective measure of sleep for this study. Missing global sleep quality index scores were handled by replacing missing component scores with the mean of the component scores available for that participant. For the current study, the 7 component scores of the PSQI showed acceptable internal consistency with α = .66.

Insomnia Severity Index

The Insomnia Severity Index (ISI) is a 7-item self-report measure that assesses the perceived severity of insomnia. The items sum to produce a total score (range, 0–28).³⁷ The ISI has convergent validity with other measures such as the PSQI (r = .67), the Dysfunctional Beliefs and Attitudes about Sleep Scale (r = .55), and sleep diaries (range, 0.32–0.91).³⁸ Clinically significant insomnia is indicated by a score of ≥ 15.³⁹ Internal consistency was high for the current study (α = .81).

Data analysis

The first aim was to describe the incidence of military and life events that had the most negative impact on sleep quality reported on the MSSA. We examined the incidence and nature of responses across the 4 sections of the MSSA to determine whether current and historical sleep-quality ratings on the MSSA were related to standard measures of sleep quality and insomnia symptoms as determined by the PSQI and ISI, respectively. Frequency (%) and mean (standard deviation [SD]) were used to evaluate the incidence and nature of current and historical sleep quality on the MSSA. Descriptives were also completed to examine the frequency of each military/life event, whether the event was perceived as impacting sleep quality, and to rank the top 3 of 6 possible military/life events that were perceived to have most negatively impacted sleep quality.

The second aim was to examine differences in sleep quality responses on the MSSA between service members who had deployed vs those who had not deployed. An independent-sample t test was used to assess group differences (deployed vs nondeployed) on continuous sleep outcomes as measured by the MSSA, PSQI, and ISI. The χ² test of independence was used to examine the association between prior deployment status and the perception that current sleep disturbance was attributable to military service (yes, no, unsure). Odds ratios and adjusted standardized residuals (z) were calculated to further describe the nature of significant χ² effects. An adjusted z < –1.96 and > 1.96 indicated that observed cell proportions significantly differed from what would be expected by chance. All analyses were completed using R version 4.0.2 (R Foundation for Statistical Computing, Vienna, Austria).⁴⁰

RESULTS

Participants

Demographic and military characteristics of the sample are presented in Table 1. There were 194 service members surveyed, representing 4 branches of the U.S. military (45.9% Air Force, 39.7% Army, 11.3% Navy, and 3.1% Marines) who on average (SD) served 16.38 (6.73) years. Participants were primarily male (63.4%, n = 123) and married (75.8%, n = 147), with a mean (SD) age of 37.82 (7.21) years. The majority were Caucasian (68.6%, n = 133), with African Americans (17.5%, n = 34) constituting the next-largest race in the cohort. Approximately three-quarters of service members (76.3%, n = 148) had deployed at least once, and more than half (53.1%, n = 103) received combat hazard pay (ie, supported a combat deployment). The scores on the PSQI ranged from 1 to 21 with a mean (SD) of 10.1 (4.60). Nearly all participants (85.1%, n = 165) reported poor sleep quality (PSQI total score ≥ 5). The service members’ scores on the ISI ranged from 4 to 28 with a mean score (SD) of 17.3 (5.32); 69.1% (n = 134) had an ISI score ≥ 15, consistent with clinically significant insomnia. These findings on the PSQI and ISI were expected given that participants were seeking treatment from a sleep disorders clinic.

Table 1.

Demographic and military service characteristics.

Characteristic	n	Mean (SD) or Percentage
Age, y	194	37.82 (7.21)
Race
African American	34	17.5
Caucasian	133	68.6
American Indian/Alaskan Native	2	1.0
Asian	6	3.1
Native Hawaiian/Pacific Islander	2	1
Other	16	8.2
Ethnicity
Hispanic	43	22.2
Non-Hispanic	150	77.3
Marital status
Single/not living with a partner	24	12.4
Married/living with partner	147	75.8
Divorced/separated/other	22	11.3
Sex
Male	123	63.4
Female	71	36.6
Education
High school diploma or equivalent	8	4.1
Some college	27	13.9
Associate degree	53	27.3
Bachelor’s degree	49	25.3
Postgraduate	56	28.9
Branch of the military
Army	77	39.7
Air Force	89	45.9
Navy	22	11.3
Marines	6	3.1
Years in military	16.38	6.73
Military grade
E-1–E-3	4	2.1
E-4–E-6	63	32.5
E-7–E-9	69	35.6
WO-1–WO-5	57	29.4
Type of duty
Combat arms	28	19.0
Combat support	39	26.5
Combat service support	80	54.4
Times deployed
0	46	23.7
1	43	22.2
2	35	18.0
3	19	9.8
4 or more	51	26.3
Deployment operations
Operation Enduring Freedom/Operation Iraqi Freedom/Operation New Dawn	133	68.6
Other*	25	12.9

Counts (%) differ across demographics based on missing or “not applicable” responses. Examples of combat arms duty include infantry, armor, field artillery, air defense artillery, special forces, and combat flight crews. Examples of combat support duty include chemical corps, engineer, military intelligence, military police including security forces, and signal corps. Examples of combat service support duty include quartermaster, ordinance, transportation including convoy personnel, finance, chaplain, judge advocate general, and medical including air evacuation crews. *“Other” deployment operations include Operation Inherent Resolve, Operation Freedom’s Sentinel, Operation United Assistance, Persian Gulf (Operation Desert Storm/Shield), Somalia (Restore Hope), Haiti (Restore Democracy), Macedonia (Able Sentry), Croatia-Bosnia (Provide Promise), Bosnia-Herzegovina (Joint Endeavor/Guard), Rwanda (Support Hope), Panama (Operation Just Cause), Lebanon, Grenada, Vietnam, and Humanitarian Operation. E-1–E-3 = junior enlisted officers, E-4–E-6 = junior noncommissioned officers, E-7–E-9 = senior noncommissioned officers, O = officer, SD = standard deviation, WO = warrant officer.

MSSA

Section 1: sleep quality and primary sleep disturbance

Sleep-quality MSSA items were rated on a Likert scale of 1–5, with 1 indicating low sleep quality and 5 indicating high sleep quality. For this article, we considered a rating of 3 to indicate average sleep quality. The average self-reported sleep-quality rating was low average in the sample, with a mean (SD) of 2.1 (0.89). A majority of service members (72.7%, n = 140) rated their overall sleep quality as low to low average. The most frequently endorsed primary problems with sleep were “trouble falling or staying asleep” (45.4%, n = 88), “lack of daytime energy” (16.0%, n = 31), and “daytime sleepiness” (10.8%, n = 21). Nearly half (45.4%, n = 88) perceived that their sleep problems resulted from military service, 45.4% (n = 88) were unsure, and only 9.3% (n = 18) indicated that they did not believe their sleep problems were caused by military service.

Section 2: service-related events impact on sleep

This section of the MSSA evaluated service members’ sleep quality across military-related events. Overall, 71.7% (n = 139) rated their sleep quality as average to high during initial training, with a mean (SD) of 3.3 (1.33). Similarly, 77.2% (n = 149) described their sleep quality as average or better during their first military assignment, with a mean (SD) of 3.5 (1.16).

Regarding PCS, 93.8% (n = 182) of service members reported at least 1 PCS, and slightly more than half (51.0%, n = 99) reported military moves between 1 to 5 times. Of those who reported a PCS, more than half (58.8%, n = 107) reported that the PCS negatively impacted their sleep quality, and a third (35.4%, n = 64) reported worsened sleep quality for more than 3 months. Among service members who reported worsened sleep for more than 3 months related to a PCS, 93.8% (n = 61) reported low to low-average sleep quality (mean [SD] 1.6 [0.60]) during that PCS.

In this sample, 76.3% (n = 148) reported at least 1 deployment (Table 1). Among those who deployed, 82.4% (n = 122) reported that it negatively impacted their sleep quality, and 91% (n = 111) reported that their sleep quality was worse for more than 3 months. Low to low-average sleep quality (mean [SD] 1.7 [0.71]) was reported by 88.3% (n = 98) of participants during the deployment that service members identified as having had the greatest negative impact on their sleep. In addition, for service members whose sleep quality worsened during deployment, 73% (n = 81) indicated that deployments affected their sleep for at least 3 months on 2 or more occasions.

For redeployment, 61.9% (n = 91) reported that this military event negatively impacted sleep quality, and 84.6% (n = 77) endorsed low to low-average sleep quality (mean [SD] 1.9 [0.76]) during the redeployment that most negatively impacted their sleep. The majority of service members (76.9%, n = 70) reported that the redeployment that most impacted their sleep was immediately after the deployment that most affected their sleep quality. All service members who reported worsened sleep quality with redeployment had 3 months or more of worsened sleep quality, and 71.4% (n = 65) noted that redeployment impacted their sleep quality 2 or more times.

Section 3: stressful life event impact on sleep

This section of the MSSA asked participants to identify stressful life events that had a negative impact on sleep quality including nonservice-related events, military-related events other than deployment, and traumatic events other than deployment (see Table 2 for complete list). The majority of service members (79.4%, n = 154) reported 1 life event and 63.4% (n = 123) reported 2 life events that had a lasting negative impact on their sleep quality. Overall, 88.3% (n = 143) of service members endorsed low to low-average sleep quality (mean [SD] 1.6 [0.72]) during the first identified life event, and 86.2% (n = 106) endorsed low to low-average sleep quality (mean [SD] 1.67 [0.77]) during the second identified life event. Figure 1 illustrates the percentages of individuals who rated their sleep quality from low–high for stressful military and life events. As the figure shows, the first and second stressful life events, followed by deployments, had the highest proportion of respondents rating their sleep quality as poor. As seen in Table 2, the most frequent first life event identified as impacting sleep quality was military-related other than deployment (45.5%, n = 70). Within this category, more than half of participants attributed their sleep disturbance to the responsibilities they had while in a specific military position (ie, typically a military leadership position such as commander or first sergeant).

Table 2.

Stressful first life event categories that negatively impacted sleep quality.

Categories	Number	%	Subtypes	% Within Category	Total %
Military service	70	45.5	Position*	54.3	24.7
			Work schedule	17.1	7.8
			Military course	7.1	3.3
			Injury/illness	8.6	3.9
			Physical training	2.9	1.2
			Other	10.0	4.5
Nonmilitary service	56	36.4	Divorce/marital issues	16.1	5.8
			Pregnancy	16.1	5.8
			Birth of child/adoption	26.8	9.7
			Child care	10.7	3.4
			Death of family member or friend	16.1	5.8
			Other	14.3	5.2
Trauma	28	18.2	Exposure to actual or threatened death	14.2	2.5
			Exposure to suicide	21.4	3.9
			Assault	7.1	1.2
			Sexual assault	32.1	5.8
			Other	17.9	4.5

Counts differ across demographics based on missing or “not applicable” responses. *Usually a military leadership position such as commander or first sergeant.

Figure 1. Self-reported sleep quality by event.

Section 4: top 3 events

In this section of the MSSA, service members were instructed to rank-order the top 3 events that most negatively impacted their sleep quality. As seen in Figure 2, deployment (40.2%, n = 78) was the event listed the most frequently, followed by the first life event (28.9%, n = 56) and the second life event (12.9%, n = 25). Further, the first life event (27.3%, n = 53), the second life event (24.2%, n = 47), and redeployment (16.0%, n = 31) were rated as the second-most significant events that had a negative impact on sleep quality. Finally, PCS (24.7%, n = 48), the second life event (15.5%, n = 30), and the first life event (16.5%, n = 32) were rated as the third-most significant events that negatively impacted sleep quality.

Figure 2. Military and life events ranked as most impacting sleep quality.

Basic = initial military training, Deploy = deployment, Redeploy = redeployment, LE = life event, Least = third most negative event, Moderate = second most negative event, PCS = permanent change of station, Worst = most negative event.

Sleep outcomes as a function of deployment

There were no significant differences in current sleep quality between service members with a history of deployment and service members who had not deployed on the PSQI (M = 10.20 ± 4.50, deployed; M = 9.74 ± 4.94, not deployed; t₁₉₂ = –0.59; P = .56), the MSSA current sleep quality item (M = 2.13 ± .85; M = 2.20 ± 1.03; t₁₉₂ = 0.45; P = .66), or insomnia symptoms on the ISI (M = 17.16 ± 5.28; M = 17.59 ± 5.49; t₁₉₂ = 0.47; P = .64), respectively. There was, however, an association between deployment and the perception of sleep problems as being military-related (χ²_{2, 194} = 7.17; P = .03). Specifically, service members with a deployment history were more than twice as likely (odds ratio, 2.61) to attribute sleep disturbances to military service as those who had not deployed, and they were overrepresented in attributing sleep disturbance to military service (z = 2.7). Service members who had not deployed were more than twice as likely (OR, 2.03) to report uncertainty about whether their sleep disturbance was because of military service compared with service members who had deployed. Further, service members who had not deployed were overrepresented in being unsure whether their sleep disturbance was because of military service (z = 2.1).

DISCUSSION

This study is the first to use the MSSA, which assesses multiple military and life events that could contribute to sleep disturbances in service members, and it reports the findings in a sample of 194 active-duty service members. The primary finding from this study was that life events (life events #1 and #2 summed, listed in Table 2) during military service were reported as the most frequent stressors to have the greatest negative impact on sleep quality, even more so than deployments. Although 76.3% of participants in this study had at least 1 previous deployment, only 40.6% reported deployment as the primary factor that negatively impacted sleep quality. Furthermore, 41.8% reported life events other than deployment as the primary factor that negatively impacted sleep quality. There were no substantial differences in sleep quality between those with a deployment history (MSSA current sleep quality, M = 2.13; PSQI, M = 10.20) and those without a deployment history (MSSA current sleep quality, M = 2.20; PSQI, M = 9.74), which is consistent with the previous literature.^1,6 Taken together, these findings indicate that life events that service members face, beyond deployments, contribute to decrements in sleep quality during a military career.

The finding that stressful life events are the most reported events contributing to disturbed sleep is similar to a report in a civilian population with both chronic and episodic insomnia.²⁰ Bastien et al (2004)²⁰ reported that the leading precipitating factors were family, health, and work-school stressful life events. The life event most reported by service members with the MSSA in this study was related to their military position (ie, what their military duties required) in nearly 25% of participants. Significant work stress has been previously reported in more than 25% of service members, and in 8% it was severe enough to affect their emotional health.¹⁶ Our findings that military duties can precipitate sleep disturbances are consistent with this previous report, noting that psychosocial stress related to work, especially in regard to high work-related demands as is required of service members, can predict the onset of insomnia.⁴¹

Nearly 10% of the sample reported that the birth of a child/adoption negatively impacted their sleep. Although it is not surprising that the presence of a new child can negatively impact sleep, this finding should be considered in light of the high rate of insufficient sleep reported by service members. In a recent study that examined sleep in service members after the birth of a child, women reported obtaining 62 minutes less sleep and men reported obtaining 13 minutes less sleep each night.⁴² In service members who regularly report obtaining 6 hours of sleep per night,¹ further decrements in sleep duration and/or quality associated with this life event could markedly affect their sleep health and duty performance.

The finding that deployment was the second most reported factor that negatively impacted sleep is not necessarily surprising in that previous studies evaluating sleep during deployment have found that sleep quality is impaired for the majority of service members.^5,6,43 Still, our study has 2 important findings regarding deployment and the long-term impact on sleep. First, the sleep disturbances that occur during deployment persist in many service members, noting that the average length of time between deployment and clinical sleep evaluation for these participants was nearly 9 years. Second, the service members who deployed compared to those who had not deployed were more than twice as likely to report that military service caused their sleep disturbance and/or disorder. Although this medical finding is self-reported, there is increasing evidence that deployment-related sleep disturbances are associated not only with insomnia³ but also with obstructive sleep apnea.⁸

Of note is the finding that initial entry training was not a frequently cited stressor on sleep, with a relatively good average sleep quality for the cohort at 3.31 on the Likert scale of 1–5, with 1 indicating low sleep quality and 5 indicating high sleep quality. In general, new military service members are healthy individuals who have minimal sleep disturbances; however, there are several studies indicating that initial-entry military training negatively impacts sleep.^10,15,44 The findings from our study suggest that decrements in sleep quality during initial training are likely short-term sleep disturbances, because sleep quality improved at their subsequent first duty assignment. These findings should be interpreted with a degree of caution because the majority of participants in this study were career individuals, many years removed from their initial entry training, and the scores reported for this section may be subject to recall bias.

Although future validation of the MSSA is required in both clinical and nonclinical populations of service members, this novel instrument has a number of possible uses in the military. Service members annually complete a periodic health assessment. The MSSA could be integrated into this assessment to screen for decreases in sleep quality that would warrant a clinical evaluation. Relevant military or life events identified from the MSSA that precipitated changes in sleep could inform provider-patient conceptualizations and treatment plans. The majority of the scientific literature on sleep disturbances in the military has focused on male service members, primarily in the U.S. Army. The use of the MSSA in larger, epidemiologic studies throughout all branches of the military could determine which time periods in a military career are best suited for targeted interventions to improve the sleep health of all service members.

Despite the novelty of this study, it does present with limitations that warrant discussion. As is the case with any questionnaire, the MSSA relies on self-reporting. It is possible that some responses related to events are biased because they may have occurred in temporal proximity to answering the questionnaire, thereby carrying a greater weight than warranted regarding the contribution to decreased sleep quality.⁴⁵ There are also some inherent limitations related to our sample. Participants were recruited while seeking treatment from a military sleep disorders clinic and were a relatively senior group of service members with an average of 16.4 years of military service. Thus, the events reported are likely more representative of service members with clinically significant sleep disorders that have developed over their military career and would not necessarily represent a more junior service member or service members without clinical sleep disturbances. Noting these limitations, the MSSA is a substantial advancement in determining events in a service member’s career, which were previously unknown, that can contribute to decrements in sleep quality.

Sleep disturbances are a known, long-standing hazard of military service⁴⁶ and have a significant negative impact on military performance, health, and resilience.⁴⁷ More recent studies have further highlighted the marked increase in generalized sleep disturbances and the diagnoses of insomnia and obstructive sleep apnea.⁸ The unique contribution of the MSSA is that it is the first military-specific sleep questionnaire and provides an enhanced understanding of the events that occur in a typical service member’s career that can precipitate sleep disturbances and the likely development of chronic sleep disorders. Further, it seems that in many service members there are multiple events, in addition to deployments, that perpetuate and/or worsen their sleep after the initial perturbation occurs. What remains unclear, however, is how younger service members or those who are not undergoing a clinical evaluation may differentially respond to the MSSA. Thus, additional examination of this measure is warranted to further validate the present findings.

DISCLOSURE STATEMENT

All authors have seen and approved the final version of the manuscript. Work for this study was completed at Wilford Hall Ambulatory Surgical Center, Joint Base San Antonio-Lackland, and at The University of Texas Health Science Center at San Antonio. This study was funded by the Defense Health Agency, the Defense Medical Research and Development Program, the Clinical Research Intramural Initiative for Military Women’s Health (DM170708; Mysliwiec), and the Air Force Research Laboratory, Wright Patterson Air Force Base, Ohio (FA8650-18-2-6953; Peterson). The views expressed herein are solely those of the authors and do not represent an endorsement by or the official policy or position of the U.S. Air Force, the U.S. Army, the Defense Health Agency, the U.S. Department of Defense, the U.S. Department of Veterans Affairs, or the U.S. government. Dr. Mysliwiec is a paid consultant for CPAP Medical, NOCTEM, and Sleep Care Inc. He has previously consulted for Bluegrass Medical, Ebb Therapeutics and Nightware. All other authors report no conflicts of interest.

ABBREVIATIONS

ISI

Insomnia Severity Index

MSSA

Military Service Sleep Assessment

PCS

permanent change of station

PSQI

Pittsburgh Sleep Quality Index

SD

standard deviation