Seasonal affective disorder (SAD) is a type of winter-time depression experienced by people those who live in northern latitudes such as those of New York, Seattle, all of Canada, and Northern Europe. I believe it is primarily a disorder of sunlight/vitamin D deficiency.
Vitamin D, when administered in late winter, produces a positive effect on mood in only five days.[1] One theory for this is that vitamin D stimulates the brain to produce more serotonin. In a wintertime experiment, serum vitamin D levels doubled in six months through supplementation and dramatically increased scores on a wellbeing assessment.[2] Two groups were given either 1,000 IU or 4,000 IU of vitamin D daily. And although both groups improved, the higher dose produced better results.
ScienceDaily (Mar. 18, 2009) - A lack of Vitamin D, due to reduced sunlight, has been linked to depression and the symptoms of Seasonal Affective Disorder (SAD), but research by the University of Warwick shows there is no clear link between the levels of vitamin D in the blood and depression.
Vitamin D vs broad spectrum phototherapy in the treatment of seasonal affective disorder.
Gloth FM 3rd, Alam W, Hollis B.
J Nutr Health Aging. 1999;3(1):5-7.
PMID: 10888476
All subjects receiving vitamin D improved in all outcome measures. The phototherapy group showed no significant change in depression scale measures. Vitamin D status improved in both groups (74% vitamin D group, p < 0.005 and 36% phototherapy group, p < 0.01). Improvement in 25-OH D was significantly associated with improvement in depression scale scores (r2=0.26; p=0.05). Vitamin D may be an important treatment for SAD. Further studies will be necessary to confirm these findings..
Can vitamin D supplementation prevent winter-time blues? A randomised trial among older women.
Dumville JC, Miles JN, Porthouse J, Cockayne S, Saxon L, King C.
J Nutr Health Aging. 2006 Mar-Apr;10(2):151-3.
PMID: 16554952
CONCLUSIONS: Supplementing elderly women with 800 IU of vitamin D daily did not lead to an improvement in mental health scores.
Association between depressive symptoms and 25-hydroxyvitamin D in middle-aged and elderly Chinese.
Pan A, Lu L, Franco OH, Yu Z, Li H, Lin X.
J Affect Disord. 2009 Feb 25. [Epub ahead of print]
PMID: 19249103
doi:10.1016/j.jad.2009.02.002
Gloth FM 3rd, Alam W, Hollis B.
Vitamin D vs broad spectrum phototherapy in the treatment of seasonal affective disorder.
J Nutr Health Aging. 1999;3(1):5-7.
PMID: 10888476 [PubMed - indexed for MEDLINE]
Benefits of Vitamin D Supplementation
Joel M. Kauffman, Ph.D.
Journal of American Physicians and Surgeons
Volume 14 Number 2 - Summer 2009
Clinical trials show that vitamin D supplementation at higher
levels than previously recommended is beneficial for many
conditions. It decreases the frequency of falls and fractures, helps
prevent cardiovascular disease, and reduces symptoms of colds or
influenza. Benefits are also seen in diabetes mellitus, multiple
sclerosis, Crohn disease, pain, depression, and possibly autism.
Sunlight does not cause an overdose of vitamin D production,
and toxicity from supplementation is rare. Dose recommendations
are increasing, but appear to be lagging the favorable trial results. A
number of common drugs deplete vitamin D levels, and others may
limit its biosynthesis from sunlight.
People with adequate levels from sun exposure will not benefit
from supplementation. While dietary intake is helpful,
supplementation is better able to raise serum 25-hydroxyvitamin D ,
the major circulating metabolite, to the level now thought adequate,
30-50 ng/mL.
Where there is inadequate daily sun exposure, oral doses of
1,000-2,000 IU/d are now considered routine, with much higher
doses (up to 50,000 IU) for rapid repletion now considered safe.
Vitamin D and mood disorders among women: an integrative review.
Murphy PK, Wagner CL.
J Midwifery Womens Health. 2008 Sep-Oct;53(5):440-6. Review.
PMID: 18761297
Four of six studies reviewed imparted significant results, with all four showing an association between low 25(OH)D levels and higher incidences of four mood disorders: premenstrual syndrome, seasonal affective disorder, non-specified mood disorder, and major depressive disorder. This review indicates a possible biochemical mechanism occurring between vitamin D and mood disorders affecting women, warranting further studies of these variables using rigorous methodologies.
Vitamin D and depressive symptoms in women during the winter: a pilot study.
Shipowick CD, Moore CB, Corbett C, Bindler R.
Appl Nurs Res. 2009 Aug;22(3):221-5.
PMID: 19616172
doi:10.1016/j.apnr.2007.08.001
ESULTS: Vitamin D supplementation was associated not only with an increase in the serum D levels by an average of 27 ng/ml but also with a decline in the BDI-II scores of an average of 10 points. DISCUSSION: This study suggests that supplemental vitamin D3 reduces depressive symptoms.