LA PERCEZIONE DEL SONNO E DEI SUOI SEGNALI NEL SOGGETTO INSONNE

The notion of “sleep perception” includes two important psychological aspects: the ability to recognize one’s own sleep, by discriminating it from the waking state, and the way in which sleep quality is judged, that is the “subjective sleep perception”. These two facets, which are strictly related, are both modulated by individual variables, such as personal emotional experience in relation to disturbed sleep, and the individual’s beliefs on what the characteristics of a “good sleep” should be (e.g., how much sleep is enough for efficient diurnal functioning). Furthermore, in a more general sense, sleep perception may also involve the ability to correctly detect signals of sleep propensity (both physiological and behavioural), which influence the subject’s choice of bedtime. Thus, from a clinical perspective, the presence of specific “sleep perception biases” may at least partly explain the development and maintenance of insomnia. First of all, insomniacs show difficulties in correctly discriminating sleep from wakefulness. They tend to overestimate the duration of waking periods, both in proximity to sleep onset and during the sleep episode, with a consequent underestimation of total sleep time. These misperceptions, together with erroneous beliefs on how long a “good sleep” should be, contribute to determine insomniac’s bad subjective perception of sleep, and thus a global dissatisfaction with its quality. Insomniacs’ sleep misperception may also concern sleep signals. This would explain their tendency to refer more to external (e.g. time of day) than to internal (e.g. tiredness, burning or heavy eyes, yawning) markers when deciding the most appropriate moment for sleep. This kind of phase shift between the individual’s decision and physiological sleep propensity may increase the subject’ s problems in falling asleep. In light of the importance of these psychological factors in the development and maintenance of insomnia, cognitive-behavioural interventions may focus on several objectives, such as: correcting beliefs on optimal sleep characteristics, improving recognition of sleep propensity signals, increasing the ability to use these signals to synchronize sleep habits with moments of maximal sleep propensity