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of tinnitus on sleep
It is important to explore the mechanisms underlying the association between tinnitus
loudness and sleep disturbances. Tinnitus loudness is a primary attribute of
tinnitus, but it is not clear whether the degree of insomnia is directly
related to tinnitus loudness or whether the degree of insomnia is related to
psychological factors such as annoyance or depressed mood. This can be assessed
analysis (Bollen 1987). The aim of mediation analysis
is to assess the direct and indirect effects of an independent variable (e.g.,
tinnitus loudness) on a dependent variable (e.g., insomnia). This is achieved
by determining whether the relationship between the independent variable and
the dependent variable changes when other independent variables are included in
the analysis. If the other variables do change this relationship, and if they
are themselves related to the dependent variable, they are known as mediator
variables (Baron & Kennedy 1986).
Dr. Aazh’s tinnitus team studied whether there was
a relationship between self-reported tinnitus loudness and insomnia and factors
mediating any such relationship. A linear regression analysis using data for
over 400 patients showed a statistically significant relationship between
tinnitus loudness as measured via visual analogue scale (VAS) and the score on
Insomnia Severity Index (ISI) (b = 1.38,
95% CI: 1.05 to 1.7) (path “a” in Figure 1).
The outcomes of the mediation analysis are summarized
in lower part of the Figure 1. The regression coefficients for the indirect
effects of tinnitus loudness on insomnia were as follows: via depression (path
“b” in Figure 1), b = 0.53 (95% CI:
0.35 to 0.71, p<0.001); via
tinnitus annoyance (path “c” in Figure 1), b= 0.33 (95% CI: -0.004
to 0.66, p = 0.053); and via tinnitus
handicap (path “e” in Figure 1), b =
0.38 (95% CI: 0.16 to 0.6, p =
0.001). The coefficient for the total indirect effect was b = 1.23 (95% CI: 0.89 to 1.58). The regression coefficient for the
direct effect of tinnitus loudness on insomnia (path “d” in Figure 1) was only b = 0.11 (95% CI: -0.27 to 0.51, p = 0.57), a small and non-significant
The mediation analysis showed that the
relationship between tinnitus loudness and insomnia was fully mediated via
depression, tinnitus handicap, and tinnitus annoyance. In other words, there
was no direct effect of tinnitus loudness on insomnia. Rather, it may be the
case that greater tinnitus loudness is associated with increased depression,
tinnitus annoyance and tinnitus handicap, and that these in turn lead to
One clinical implication of this finding is
that, for patients who suffer from tinnitus, insomnia may be alleviated if
tinnitus annoyance, tinnitus handicap and tinnitus-induced depression are
managed adequately, even if the tinnitus loudness remains unchanged. Past
research has shown that although various forms of tinnitus rehabilitation only
minimally reduced the loudness of tinnitus, the handicap and annoyance produced
by the tinnitus and depressive symptoms typically improved considerably (Aazh et al. 2008; Aazh & Moore 2016; Martinez-Devesa et al. 2010). Hence, such
rehabilitation is likely to reduce problems with insomnia.
A common concern expressed by patients is that although they can cope with
the current loudness of their tinnitus, their biggest fear is that if their
tinnitus gets louder it may prevent them from sleeping at nights, leading to a
constant state of fatigue that they would not be able to cope with. It may be
helpful to such patients to inform them about the outcome of this study. They
can be reassured that, although there is no proven method to decrease the loudness of tinnitus,
rehabilitative procedures can reduce the impact of tinnitus on their life and
decrease their emotional reaction to the tinnitus, thereby reducing the impact of tinnitus on
their ability to sleep.
Aazh, H., &
Moore, B. C. J. (2016). A comparison between tinnitus retraining therapy and a
simplified version in treatment of tinnitus in adults. Auditory and Vestibular Research, 25, 14-23.
Aazh, H., Moore, B. C. J., & Glasberg, B. R. (2008). Simplified
form of tinnitus retraining therapy in adults: a retrospective study. BMC Ear Nose Throat Disord, 8, 1-7.
Baron, R. M., & Kennedy, D. A. (1986). The moderator-mediator
variable distinction in social psychological research: Conceptual, strategic,
and statistical considerations. Journal
of Personality and Social Psychology 51, 1173-1182.
Bollen, K. A. (1987). Total, direct and indirect effects in
structural equation models. Sociologoical
Methodology 17, 37-69.
Martinez-Devesa, P., Perera, R., Theodoulou, M., et al. (2010).
Cognitive behavioural therapy for tinnitus. Cochrane
Database Syst Rev, Cd005233.