People troubled by depression usually experience their dark moods in an on-again, off-again fashion. In that respect, seasonal affective disorder (SAD) differs only in that the oscillations follow a seasonal schedule, with the depression usually starting in the fall and lasting through the spring. Lack of light is often blamed for SAD, but just how darker days cause depression in SAD sufferers is still in question, reports the January 2008 issue of the Harvard Health Letter.
Experts debate whether it has been proved that lack of sunlight in winter triggers SAD, but there’s certainly circumstantial evidence to support the connection. How might lack of light cause depression? The Harvard Health Letter discusses three theories:
To continue reading this article, you must log in.
Subscribe to Harvard Health Online for immediate access to health news and information from Harvard Medical School.
- Research health conditions
- Check your symptoms
- Prepare for a doctor's visit or test
- Find the best treatments and procedures for you
- Explore options for better nutrition and exercise
I'd like to receive access to Harvard Health Online for only $4.99 a month.Sign Me Up
Already a member? Login ».
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.
No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.