Changing the timing of when you are awake and when you sleep can profoundly affect your mood, according to scientists who have for the first time linked mood changes to the predictable and enduring internal rhythms of the human body.
Two studies released Tuesday tease apart the complex relationships between daily biological rhythms, sleep choices and whether people feel cheerful or blue.
The studies suggest, for example, that even if a person has gotten enough sleep, he is likely to be irritable if his waking hours center on a time when his biological clock tells him he “should” be asleep.
Conversely, even if a person is sleep-deprived, he may say he feels terrific if you ask him about his mood at an hour when his biological clock tells him he is supposed to be awake, findings suggest.
The studies show that “some hours of the day, we’re happier than others, and it’s occurring inside us, not just in reaction to the world around us,” said psychologist David F. Dinges of the University of Pennsylvania.
The studies are described in the February issue of the Archives of General Psychiatry, released Tuesday by the American Medical Association.