Those most at risk are female, are younger, live far from the equator, and have family histories of depression, bipolar disorder, or SAD.
Phase-shift hypothesis:Posits that there is an optimal relationship in the alignment of the sleep-wake cycle and the endogenous circadian rhythm. During the fall and winter, as day length shortens, the circadian rhythm begins to drift later with respect to clock time and the sleep-wake cycle. This phase delay is hypothesized to bring about mood symptoms
One method to measure this circadian misalignment is known as the phase-angle difference (PAD), and is calculated as the difference in time between the dim light melatonin onset (DLMO, the time of evening rise in melatonin) and mid-sleep
Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria:Criteria for depression with a seasonal pattern include having depression that begins and ends during a specific season every year (with full remittance during other seasons) for at least 2 years and having more seasons of depression than seasons without depression over a lifetime.
Seasonal pattern disorders occur most frequently in winter although they can also occur in summer.
- Seasonal Pattern Assessment Questionnaire (SPAQ): Retrospective, self-administered tool that screens for the existence of SAD and S-SAD.
Treatment approaches typically include combinations of antidepressant medication, light therapy, Vitamin D, and counselling.
Bright light therapy (BLT)First-line treatment of SAD. BLT may function by either correcting the winter circadian rhythm phase delay or by increasing synaptic serotonin, possibly in the serotonin-rich midbrain, a target of retinofugal pathways or indeed, by both mechanisms
Antidepressant therapy:SAD, like other depressions, is believed to be associated with a dysfunction in brain serotonin activity. Therefore, second generation antidepressants (SGAs) are preferred.
- Selective Serotonin Reuptake Inhibitors (SSRIs): Fluoxetine (Prozac)
Vitamin D supplementation:Many people with SAD and S-SAD have insufficient or deficient levels of Vitamin D abd taking 100,000 IU daily may improve their symptoms
- Cognitive Behavioral Therapy (CBT)
- Transcendental Meditation (TM) and other forms of mindfulness, yoga, walking, and exercise that is personally enjoyable