Approximately 50 percent of tinnitus patients report tinnitus-related sleep disturbance, which may result from the strengthening of the tinnitus signal caused by abnormal internal auditory gain related to near-silent sleep environments (Tyler. J Speech Hear Disord 1983;48:150-154). As tinnitus signal strength increases, negative engagement of the limbic and autonomic nervous systems increases, resulting in sleep-disturbing physiological arousal and alertness.
Sound enrichment restores lateral inhibition and decreases abnormal internal auditory gain, thereby reducing tinnitus signal strength and the resulting physiological arousal and alertness. Bedside sound generators are routinely recommended for bedtime sound enrichment to facilitate falling and staying asleep. The soothing quality of nature sounds also facilitates the relaxation response.
Landscomb reported that mean scores on the Pittsburgh Sleep Quality Index (PSQI) improved significantly (p < .01) among a group of 35 tinnitus subjects who used bedside sound generators (Landscomb. Acta Otolaryngol Suppl 2006;:59-63). She also reported the specific sound chosen by the individual subject was based primarily on liking the sound rather than on evaluating its actual effectiveness. She focused on the specific sounds the subjects preferred to use, and we chose to examine sleep improvement ratings reported by device users and health factors that may affect those ratings.
Questionnaires were mailed to 526 device users randomly selected from a pool of 986. Each subject had 6-12 months of experience using a specific commercially available device. A total of 230 questionnaires were returned (43.7% return rate), of which 36 were excluded because of unilateral tinnitus (11) or multiple/absent responses (25). All 184 included subjects (35% useable return rate) were male and reported bilateral tinnitus. Subjects were asked to rate their subjective sleep improvement using a 1-10 scale, where 1 meant “no sleep improvement at all” and 10 meant “as much sleep improvement as you can imagine.”
HEARING LOSS & SOUND ENRICHMENT BENEFIT
We reasoned that sound enrichment can only be effective if the sound is audible. Hearing status was evidenced by hearing aid use in this group of 184 subjects. There were 140 hearing aid users (H-Aid=YES, 76.1%) and 44 non-aid users (H-Aid=NO, 23.9%). Figure 1 reveals the differences in mean right- and left- ear pure-tone thresholds for the two groups of subjects was substantial.
We calculated the binaural 3-frequency averages (.5, 1, and 2 kHz) and the binaural 4-frequency averages (1, 2, 3 and 4 kHz) using standard weighting [(5 x better ear = poorer ear)/6/]. Figure 2 reveals the large differences in values between the two groups. Mann-Whitney Rank-Sum tests revealed that the binaural 3-frequency and 4-frequency averages for the H-Aid = YES group were significantly greater than those for the H-Aid = NO group (p < .02). Cohen's d for each comparison also is shown for the two comparisons.
SLEEP-DISRUPTING HEALTH DISORDERS
Multiple sleep-disrupting health disorders are fairly common among the general population. We selected five specific sleep disorders that were the most common we typically encountered.
Obstructive sleep apnea (OSA): Sufferers may experience dozens of arousal-inducing episodes per night (Fairbanks. Snoring and Obstructive Sleep Apnea (3rd Ed.) 2003; Raven Press: New York). Heistand, et al. found that in a group of 1,506 subjects, 31 percent of men and 21 percent of women met OSA risk criteria (Heistand. Chest 2006;130:780-786).
Chronic obstructive pulmonary disorder (COPD): Hypo-ventilation may lead to hypoxemia, especially during REM sleep. Low-blood oxygen levels may lead to an increased number of arousals and increased sleep disruption. Weitzenblum, et al. reported that COPD affects approximately 10 percent of men over age 40 (Weitzenblum. Rev Mal Respir 2010;27:329-340).
Nocturia related to benign prostatic hypertrophy (BPH) or prostate cancer (CA): Bal, et al. reported that 70 percent of BPH patients reported nocturia and resulting sleep interruption with daytime sleepiness. (Bal. Urology 2012;80:383-388). Namiki, et al. found that in a group of 581 men with prostate cancer, 189 (32%) reported one void per night and 345 (59%) reported two or more voids per night (Namiki. Qual Life Res 2011;20:1609-1615).
Chronic pain: Covarrubias-Gomez and Mendoza-Reyes reported that in a group of 311 subjects with chronic pain unrelated to cancer, scores on the Pittsburgh Sleep Quality Index categorized 276 (89%) as poor sleepers (Covarrubias-Gomez. J Pain Palliat Care Pharmacother 2013;27:220-224).
Restless legs syndrome (RLS): Lin, et al. reported that in a group of 1,185 sleep clinic patients, 18 (1.5%) were diagnosed with primary RLS (Lin. PLoS One 2013;8:e71499). Montplassir, et al. found that in a group of 133 RLS patients, 85 percent reported difficulty falling asleep and 86 percent reported difficulty staying asleep (Montplassir. Mov Disord 1997;12:61-65).
Table 1 reveals the number and percentage of subjects who experienced these common sleep-disrupting health disorders. Four subjects had overlap syndrome, in which both sleep apnea and COPD co-exist. Various ICD-9-CM organic sleep disorders codes beginning with “327” were all categorized as other specific sleep disorders. A total of 36 percent of these subjects had been diagnosed with two or more sleep-disrupting health disorders.
MENTAL HEALTH STATUS
Mental health patients compose up to 40 percent of all patients with disturbed sleep (Ford. JAMA 1989;262:1479-1484). Benton reported that 69 percent of tinnitus patients treated at the Atlanta VA Medical Center previously had been diagnosed with at least one mental health disorder, and 48 percent of those patients had been diagnosed with two or more mental health disorders (Benton. 2013; Joint Defense-Veterans Audiology Conference: Nashville, TN). The current study fond 94 subjects (51%) had been diagnosed with two or more mental health disorders, of which the most common were depression and PTSD.
The percentage of subjects reporting each numerical sleep improvement rating and the arbitrarily assigned sleep improvement categories are shown in Figure 3. A total of 79 percent of device users reported moderate or high sleep improvement.
The sleep-improvement ratings were subjected to statistical analysis. Not surprisingly, there was a significant relationship between sleep-improvement rating and weekly number of devices uses (r = 0.473, p < .001). Subjects who reported greater sleep improvement used their devices more often than those who did not.
Four mental health groups were created: No MH Diagnoses (n = 82), PTSD Only (n = 22), Depression Only (n = 22), and PTSDS+Depression (n = 28). A 4 x 2 x 2 [Mental Health Status (4 groups) x Aided Status (Yes/No) x Sleep Health Issue] ANOVA was planned, but because of empty ANOVA cells, only a 2 x 2 x 2 [Mental Health Status (Yes/No) x Aided Status (Yes/No) x Sleep Health Issue (Yes/No)] ANOVA could be completed. Only the main factor of Mental Health Status was significant: f (1, 186) = 10.572 (p = .001). As shown in Figure 4, the mean sleep-improvement rating of subjects with diagnosed mental health disorders (MH = YES) was significantly higher than that of those without (MH = NO). However, Cohen's d revealed that the effect of mental health status on sleep improvement ratings was small (0.29).
ANOVA was completed with the four mental health groups as the independent factor. No significant differences in sound generator sleep improvement were observed among the four mental health groups (H = 5.571, 3 d.f, p = .134), as shown in Figure 5.
Bedside sound generators provide substantial sleep improvement for most users (79%). Subjects with mental health diagnoses reported significantly greater sleep improvement than those without, although the effect was small. This finding most likely is a result of poorer sleep baseline that frequently occurs in those with mental health diagnoses (Boland. Psychiatr Clin North Am 2015;38:761-776). Neither common sleep-disrupting health disorders nor hearing status as evidenced by hearing aid use had any significant effect on sleep improvement ratings. The significant relationship between sleep-improvement ratings and weekly number of devices uses begs the question: did subjects use their devices more often because they achieved greater sleep improvement, or did they achieve greater sleep improvement because they used the devices more often? The current study cannot answer that question.
These findings confirm the anecdotal reports of sleep improvement among tinnitus sufferers when bedside sound generators are used. Use of standardized sleep measures for both baseline and post-device usage may provide greater insight into both the nature of sleep improvement provided by these bedside sound generators.