The relationship between seasonal affective disorder (SAD) and subjective quality of sleep/wake cycle in adolescents was explored. The Seasonal Pattern Assessment Questionnaire for Children and Adolescents (SPAQ-CA) and Mini Sleep Questionnaire (MSQ) were administered to 345 adolescents living in the city of Cesena (Emilia-Romagna region, Italy) (299 females; age range: 14–18 years), to determine SAD and perceived quality of the sleep/wake cycle. The response rate was 92% for females and 90.2% for males. The MSQ includes two factors, sleep and wake, with lower scores corresponding to a lower quality of sleep and wake. The MSQ includes cut-off criteria to detect a good or bad sleep and wake quality. Adolescents with SAD (16±5.7) scored significantly lower than those not affected on wake factor (19.5±4.3), while no effect has been observed on sleep factor. SAD was the only one significant predictor of good/bad wake quality, while it did not reach significant level with reference to good/bad sleep quality. Present results are indications of a possible influence of SAD on wake quality and further studies are necessary to confirm them.
The relationship between sleep and depression has been deeply explored in the last decades, as reported in three reviews (Riemann et al., 2001, Ivanenko et al., 2005 and Tsuno et al., 2005), showing a bi-directional relationship between them. Specifically, some sleep markers of depression are early morning awakening and shorten REM sleep latency (Srinivasan et al., 2009). On the contrary, hypersomnia is related to some sub-types of depression, as the seasonal affective disorder (SAD) (Thompson and Isaacs, 1988, Allen et al., 1993 and Tam et al., 1997), which is characterized by recurrent depressive episodes that occur annually in the fall and winter (Rosenthal et al., 1984), with a summer variant of SAD characterized by periodic depressive episodes in this season (Wehr et al., 1987). SAD patients also present awakening difficulties (Avery et al., 2002).
It is well known that the prevalence of SAD changes with age. In particular, during adolescence, the frequency of SAD raises compared to childhood (Swedo et al., 1995 and Tonetti et al., 2007). This increase has been linked to the strong hormonal changes, occurring during this period (Swedo et al., 1995). To date only two studies (Swedo et al., 1995 and Tonetti et al., 2007) have been carried out on the features of SAD during adolescence and the relationship between this disorder and the features of the sleep/wake cycle in this age stage has been neglected.
Our study aimed to fill this lack of knowledge, investigating the association between SAD and the perceived quality of the sleep–wake cycle in adolescents. Since adult SAD patients mainly present hypersomnia and awakening difficulties (Thompson and Isaacs, 1988, Allen et al., 1993, Tam et al., 1997 and Avery et al., 2002), we could expect a lower wake quality in SAD adolescents compared to those not affected by this disorder.
To sum up, this is the first study that explored the relationship between SAD and the sleep/wake cycle quality in a sample of adolescents. Despite the above-mentioned limitations, the present work showed that adolescents with a possible diagnosis of SAD had a worse perceived wake quality compared to those not affected, but not a significantly different subjective sleep quality.
