آلکسیتیمیا و بی خوابی

The purpose of the present study was (1) to investigate the association between insomnia and alexithymia, as measured by the Toronto Alexithymia Scale (TAS-20) and its subscales, and (2) to test if the TAS-20 and its subscales show the same correlational pattern with anxiety, depression and perfectionism in insomnia patients as has previously been found in non-clinical samples. A consecutive series of 259 insomnia patients were compared with a community sample. Although the insomnia patients scored significantly higher on the TAS-20, this difference disappeared when trait anxiety was controlled for, and was primarily due to patients who suffered from insomnia associated with another psychiatric disorder. All insomnia groups, however, showed elevated scores on the TAS-20 subscale Externally Oriented Thinking (EOT). The correlational analysis showed moderate to high correlations between the TAS-20 (and its subscales Difficulties Identifying Feelings and Difficulties Describing Feelings, although not the EOT) and measures of depression, anxiety and perfectionism, thus replicating a pattern from non-clinical samples. The results are discussed in terms of externally oriented thinking being an interesting dimension of alexithymia, which is (a) not confounded by negative emotion and standards of performance, and (b) shows generally elevated scores in insomnia patients.

The construct of alexithymia developed from clinical observations that many patients with psychosomatic disorders had difficulty talking about feelings and fantasies (Sifneos, 1973). This led to a definition of alexithymia that emphasized difficulties in identifying and describing emotions, and in differentiating between emotions and bodily sensations. In Taylor, Bagby, and Parker’s (1997) formulation of the theory, alexithymia is assumed to involve an impaired capacity to construct mental representations of emotions, which are needed both for the cognitive processing of emotional experiences and for the verbal communication of emotional experiences to other people – two essential forms of emotional regulation. As a result of these difficulties, alexithymic individuals are assumed to be susceptible to the development of various somatic and mental disorders. Although alexithymia has been argued to play an important role in both mental and somatic disorders, little research has been done on the possible role of alexithymia in sleep disorders. The main purpose of the present study was to study the association between insomnia and alexithymia, as measured by the Toronto Alexithymia Scale (TAS-20). The TAS-20, which is the most commonly used measure of alexithymia, is a self-assessment instrument with three subscales: Difficulties Identifying Feelings (DIF), Difficulties Describing Feelings (DDF), and Externally Oriented Thinking (EOT). In previous research, some evidence of an association between insomnia and alexithymia has been reported by Pallesen et al. (2002), who found that a sample of elderly insomniacs scored significantly higher than good sleepers on the TAS-20, and in particular on the DIF subscale. There is also some evidence of an association between alexithymia and self-reported poor sleep in non-clinical samples (Hyyppää, Lindholm, Kronholm, & Lehtinen, 1990). Further, Bazydlo, Lumley, and Roehrs (2001) found an association between alexithymia and polysomnographic measures of poor sleep in a non-clinical sample, although De Gennaro et al. (2002) could not replicate this finding. It is known that insomnia may occur both as an independent disorder (so-called primary insomnia), and in connection with psychiatric conditions like depression and generalized anxiety disorder (American Psychiatric Association, 1994). This raises the question whether a possible association between insomnia and alexithymia holds both for insomnia generally or merely for anxiety- or depression-related insomnia. If the latter is the case, the association between insomnia and alexithymia should disappear when anxiety and/or depression is controlled for. Consistent with the latter hypothesis, De Gennaro, Martina, Curcio, and Ferrara (2004) found that, although the TAS-20 correlated significantly with self-report measures of poor sleep, these associations disappeared when depression was controlled for. Several studies have shown moderate to strong correlations between the TAS-20 and not only depression, but also trait anxiety (e.g., Bagby, Parker, et al., 1994, De Gucht et al., 2004, Luminet et al., 1999, Lumley et al., 1996 and Lundh and Simonsson-Sarnecki, 2001), and some evidence suggests that the association with trait anxiety may be even stronger than that with depression (e.g., Berthoz, Consoli, Perez-Diaz, & Jouvent, 1999). This makes it important to control also for anxiety when studying the association between alexithymia and insomnia. One main purpose of the present study was therefore to compare different subdiagnostic groups of insomnia patients with regard to their scores on the TAS-20. If alexithymia as measured by the TAS-20 is associated with anxiety and depression, but not with insomnia as such, patients with insomnia associated with other psychiatric disorders should have elevated scores on the TAS-20, whereas patients with primary insomnia should not. Further, elevations on the TAS-20 in the insomnia group should disappear when anxiety or depression is controlled for; in the present study we controlled for trait anxiety. Another main purpose of the present study was to contribute to the critical discussion of the TAS-20 as a measure of alexithymia, by studying the divergent validity of the three subscales of the TAS-20 in patients with insomnia. Although the TAS-20 is generally assumed to be the best-validated measure of alexithymia today, it suffers from a number of potential sources of error. As argued by Lundh, Johnsson, Sundqvist, and Olsson (2002), some of these problems are more acute with the TAS-20 subscales DIF and DDF (which require the individual to assess his or her capabilities of identifying and describing feelings) than with the subscale EOT (which asks about aspects of the person’s direct experience, as for example being more focused on external facts than on internal experiences). First, it is known that (a) self-assessment of traits relies on information that is retrieved from semantic memory (e.g., Klein, Sherman, & Loftus, 1996), and that (b) people are better able to retrieve information of the same affective tone as their current mood (Blaney, 1986 and Ellis and Moore, 1999). Because beliefs about “being able to” have a positive affective tone, whereas beliefs about “being unable to” have a negative affective tone, it seems likely that a positive mood may make it easier to retrieve beliefs about one’s ability to identify and describe emotions, whereas a negative mood may make it easier to retrieve information about difficulties and deficiencies in the same regard. This suggests that individuals in a positive mood are likely to receive too low scores on the DIF and DDF, whereas individuals in a negative mood are likely to receive too high scores on the DIF and DDF. This, however, is likely to be less of a problem with the EOT, which asks for the degree to which people focus on external facts or internal experiences – a question which is not equally related to emotional valence. Consistent with this, previous research has shown that the TAS-20 and the DIF and DDF subscales, but not the EOT subscale, correlate positively with measures of anxiety and depression (Bagby, Taylor, et al., 1994, Berthoz et al., 1999 and De Gucht et al., 2004). Second, being able to report about one’s own capabilities seems to require a more complex cognitive process than merely reporting aspects of one’s direct experiences. Judging one’s capabilities requires an evaluation of performance relative to some personal standard, and a crucial question is therefore how stringent standards people have for judging their performance. For example, individuals with high personal standards for what counts as being good at identifying and describing emotions are likely to receive too high scores on the TAS-20, whereas individuals with low standards in this regard are likely to receive too low scores. Lundh et al. (2002) reasoned that if personal standards are important to the self-assessment of DIF and DDF but not EOT, then the DIF and DDF but not the EOT should correlate with measures of perfectionism (defined as the desire to achieve high standards of performance, in combination with overly critical evaluations of one’s performance). In two separate studies, with the two different measures of perfectionism, they found support for this hypothesis in the form of moderate to strong correlations between perfectionism and DIF and DDF, but not EOT. A second main purpose of the present study was, therefore, to study the association between the three different dimensions of TAS-20 alexithymia and anxiety, depression and perfectionism in patients with insomnia. First, it is of interest to see if the correlational pattern that has been found in non-clinical samples – that is, the DIF and the DDF but not the EOT correlating with anxiety, depression and perfectionism – is found also in insomnia patients. Second, if this is the case, the question must be raised what this means for the interpretation of the results on the TAS-20 in insomnia patients. To summarize, the purpose of the present study was to test two sets of hypotheses. First, it was hypothesized that, if there is an association between insomnia and alexithymia, this association is due to anxiety and/or depression and not to insomnia as such. Thus we predicted (a) that the insomnia group will not differ from the control group on the TAS-20 when trait anxiety is controlled for, and (b) that elevated scores on the TAS-20 and its subscales are likely to be found mainly in the subdiagnostic group of insomnia associated with other psychiatric disorders. Second, it was hypothesized that the TAS-20 factors DIF and DDF, but not EOT, correlate positively with anxiety, depression and perfectionism in insomnia patients, as they have been found to do in non-clinical samples.