Sleep disturbances are a key feature found in patients with
a major depressive disorder (MDD). Most patients suffer
from difficulties with falling and staying asleep, early morning
awakenings, and nonrestorative sleep [1]. Sleep disturbances
are perceived as distressing and debilitating. These disturbances
can lead to fatigue and social and occupational
dysfunction [2] and are an important reason to seek medical
attention [3].The prevalence of DSM-IV primary insomnia in
the general population is about 6% [4] versus 60–90% of
patients diagnosed with MDD [5, 6], with the highest prevalence
proportions found in inpatients [7].