Final answer:
Early morning awakening is the most typical effect of depression on nocturnal sleep, characteristic of the sleep disturbances associated with depressive disorders.
Step-by-step explanation:
The most typical effect of depression on nocturnal sleep is often early morning awakening. Depression commonly affects various aspects of sleep, such as experiencing trouble falling asleep (initial insomnia), staying asleep (middle insomnia), or waking up too early and being unable to go back to sleep (early morning awakening). Among these, it is early morning awakening that is especially characteristic of depression. Sleep deprivation, regardless of the cause, can lead to several negative consequences, including an increase in symptoms of depression, reduced cognitive function, and decreased mental alertness. Additionally, consistent difficulty in falling or staying asleep is known as insomnia, which is distinctly associated with depression and is a prevalent sleep disorder.