\u2018Circadian Depression\u2019 May Overlap With Seasonal Depression, but Researchers Say It\u2019s Not Identical<\/p>\n
Seasonal affective disorder (SAD)<\/a>, a type of depression that waxes and wanes with annual weather patterns, seems to involve circadian rhythm disturbances, too, but it\u2019s a much narrower concept, says Dr. Tonini.<\/p>\n Seasonal mood changes are only one of the six markers of circadian depression. In the study, about 41 percent of people with circadian depression had them.<\/p>\n People with circadian depression were also more likely to report a bipolar disorder<\/a> diagnosis and to meet criteria for atypical depression<\/a>, a type marked in part by sleeping too much and weight gain, says Kruse.<\/p>\n \u201cRather than completely separate kinds of depression, these features are likely distinct but overlapping dimensions of the illness,\u201d she says.<\/p>\n Light Therapy May Help Depression, but Evidence for Melatonin Is Limited<\/p>\n The study didn\u2019t test light therapy<\/a> or melatonin<\/a>,<\/p>\n