The days are short.
SAD is associated with abnormal circadian rhythm and neurotransmitter balance triggered by alterations in dark-light cycles and melatonin release from the pineal gland.
Melatonin, vitamin D, serotonin and catecholamines (norepinephrine/“adrenaline”) may all be linked to seasonal affective disorder, but no single cause has been identified (1).
Light exposure upon waking is thought to protect against feelings of depression, while exposure to light during the night may also disrupt melatonin production and affect sleep-wake cycles.
Disturbances in sleep are closely associated with lowered mood and changes in melatonin release (2).
One theory is that because the days are shorter in the winter with later sunrises and earlier sunsets, but other factors such as vitamin D status, and serotonin regulation may also play important roles.
Signs and Symptoms of SAD:
Changes in sleep and circadian rhythm are the most prevalent signs of depression. Someone with SAD symptoms may recognize:
- Difficulty falling asleep
- Decrease in total sleep time and efficiency
- Early Morning waking
- Rapid Eye Movement Sleep Alterations.
- Changes in Temperature regulation
- Altered timing of peak cortisol release
- Daily changes in mood (3; 4)
According to the U.S. National Library of Medicine, SAD is also characterized by:
- Increased appetite and weight gain
- Increased sleepiness and daytime sleepiness
- Less energy and ability to concentrate in the afternoon
- Loss of interest in work or other activities
- Slow, sluggish, lethargic movement
- Social withdrawal
- Unhappiness and irritability
Proposed Causes of SAD:
- High levels of stress and cortisol release are associated with low melatonin production.
- Alcoholism can affect serotonin balance and may occur alongside SAD (5).
- Serotonin balance can also be affected by:
- Surges of insulin caused by blood sugar dysregulation
- Excess caffeine
- Adrenal Stress
- Excess Nicotine
- Norepinephrine imbalance
- Some individuals may be more genetically vulnerable to SAD as directed by multiple genes on multiple chromosomes (6) .
Medical Treatment of SAD:
Medical Treatment of SAD may incorporate certain prescription drugs:
- Antidepressants that target serotonin or norepinephrine receptors (9).
- or Agomelatine, an anti-depressant specifically targeting melatonin receptors (10) .
Melatonin is produced in the pineal gland and release is partly controlled by light-sensitive pigments in the retina known as Melanopsin.
The body synthesizes melatonin from tryptophan and serotonin with help from B-vitamin cofactors.
Food sources of tryptophan include fleshy meats such as turkey, beef, liver, salmon, lamb, scallops, snapper, halibut, and chicken breast, and other non-meat sources such as mushroom, spinach, raw tofu, and soybeans.
Supplements that may promote serotonin levels include: St. John’s Wort, SAMe, and 5-HTP. *It is important to be mindful of nutrient-drug interactions such as with anti-depressants.
Melatonin not only promotes sleep but is also a potent antioxidant that may offer cancer-protective benefits (11).
Other studies report seadative, anxiolytic, antidepressant, anticonvulsant, and analgesic properties (12).
There is a close association between disruptions in melatonin production and the occurrence of depressed mood (13).
Dosages of melatonin vary depend on the resource you read. Melatonin should not be used if you are taking benzodiazepines, alcohol, or other nervous system depressants.
- A low dose of 0.3mg may be safe over long periods of time, while “clinical” doses of 3-5mg or higher may be safe over the course of a few months to a year.
- Some studies suggest safety at higher doses at 10-40mg when used only for a few weeks, and 100mg when used for only 1-2 days.
- One should be cautious for use with those prone to seizures, especially children, and for those concerned about potential reproductive side effects from chronic melatonin use.
Short-term side effects may include “heavy-headedness”, vivid dreaming, or increased drowsiness upon waking. Mixed studies exist regarding both protection from and promotion of seizures.
High doses and/or chronic usage of melatonin can alter pituitary feedback loops of other hormones. The reproductive system is known to be affected and melatonin may decrease fertility in both men and women!
As melatonin is a hormone and may interact with existing medications, it is generally recommended to seek advice on usage and dosage from a qualified health professional.
Vitamin D and Seasonal Affective Disorder:
Vitamin D is a bit of a misnomer as it is actually a hormone, not a vitamin.
Vitamin D is produced in the skin from exposure to sunlight, sent to the liver to be converted to a pro-hormone, and finally activated by the kidney or immune system for activity in the body.
The Institute of Medicine recently recommended an increase of Vitamin D intake from 400IU/day to 600-800IU, and many health professionals now recommend that serum 25-OH Vitamin D levels be between 40-80nmol/L, with 50-70nmol/L being “optimum”.
Vitamin D may help improve mild depressive symtpoms, but researchers posit that it is too early to conclude a strong relation to depression (14) .
Low Vitamin D3 levels may increase risk of SAD, as well as other neurological disorders such as multiple sclerosis, Alzheimer’s, Parkinson’s disease and schizophrenia (15) .
It is thought that low Vitamin D status as an infant and child may actually predispose you to an altered psychiatric state in adulthood (16).
For more information regarding Vitamin D:
- Why is Vitamin D Important
- The Importance of Vitamin D During Pregnancy and Beyond (Part 1)
- The Importance of vitamin D During Pregnancy and Beyond (Part 2)
Light Deprivation and Bright Light Therapy for SAD:
Beyond stimulating vitamin D production, bright light can also stimulate healthy melatonin production.
Light boxes vary in style and intensity, but a 10,000lux light box (affiliate, non-affiliate) seems to work well at 30 min/day exposure upon waking. Lower intensities such as a 2,500 lux light box may require two hours to see effectiveness.
Some individuals report improvements with as little as 15 minutes a day using higher lux models.
Light therapy seems to work best directly upon waking as exposure to light during the evening may disrupt melatonin production.
Alternative Herbs and Supplements for SAD:
According to an article published in the Journal of Affective Disorders: Rhodiola rosea, chromium, 5-HTP, and inositol supplementation may act as natural anti-depressants.
Chromium has specifically been suggested to support seasonal affective disorder (19).
As mentioned earlier, St. John’s Wort may be helpful for depression as it is thought to support serotonin production. Kava is a lesser known and controversial root that may help with generalized anxiety (20).
Social Factors and Winter Depression:
Mixed opinions suggest that certain careers may pose increased risk for SAD, particularly night-shift workers. Those working in an office environment with little exposure to sunlight may also be at risk.
Lifestyle Recommendation Summary for Seasonal Affective Disorder-Winter Depression:
- Eat a low-glycemic, blood-sugar friendly diet
- Reduce caffeine intake
- Seek stress-reducing activities such as meditation, yoga, deep breathing, and exercise.
- Ensure adequate vitamin D status within the recommended "healthy range" of 40-80nmol/L.
- Sleep in a dark room and consider purchasing “blackout blinds”. Blue lighting may improve sleep.
- Seek out early morning exposure to bright light, or purchase a 10,000lux light box.
- Consume foods high in tryptophan.
- Consider medical treatment with anti-depressants such as agomelatine.
- Consult a natural health professional on personal use of one or more of the following herbs and supplements: Vitamin D, Melatonin, St. John’s Wort, SAMe, 5-HTP, stress-reducing and blood-sugar balancing herbs & supplements.