Understanding Seasonal Affective Disorder (SAD): Mood, Energy and Appetite

Content warning: The following article contains some distressing material regarding suicidal thoughts. If you need support now, call or text 988 (24/7, across Canada). If you or someone else is in immediate danger, call 911. The Hope for Wellness Helpline is also available 24/7 to all Indigenous people across Canada: 1-855-242-3310.

If you live in Canada, you'll be all too familiar with our long, dark winters. But seasonal changes in daylight may also affect your health, from your mood to your energy levels and even your relationship with food.

This may be due to a recognized pattern of depression known as Seasonal Affective Disorder (or SAD).

Article summary:

• SAD is a type of depression, which is most common during the fall and winter months. Its exact cause is still unknown, but researchers have linked it to a lack of sunlight. Less sunlight exposure may disrupt your balance of serotonin (mood-balancing brain chemical) and melatonin (sleep hormone).
• SAD can impact both your mental and physical wellbeing, leading to low mood and carbohydrate cravings.
• If you're experiencing SAD, help is available. Speak to your family doctor about the mental health support available or, for additional resources and programs, reach out to Canadian Mental Health Association (CMHA) and Mood Disorders Society of Canada (MDSC). In this article, we've also provided some tips to help manage SAD from the comfort of home.

What is Seasonal Affective Disorder (or SAD)?

SAD is a type of depression that tends to return at the same time each year. Triggers and signs may vary from person to person, but they often appear in fall or winter. In spring, as the weather improves and longer daylight hours are noticeable, people with SAD may find their symptoms improve.

There are two types of SAD: winter-pattern and summer-pattern. However, summer-pattern SAD is less common. In this article, we're going to focus on winter-pattern SAD.

What causes SAD?

The exact cause of SAD is still unknown, but it has been linked to a lack of sunlight exposure. [1]

During the winter months, we're typically exposed to less sunlight. This can impact your body in several ways:

Serotonin decrease

Lower sunlight levels can cause a drop in serotonin, a chemical in your brain that helps manage mood. [2]

Research suggests that people with SAD may find it harder to maintain balanced serotonin levels during darker months, which can raise the risk of seasonal depression. [1]

Melatonin increase

Darkness triggers the production of melatonin, the hormone that makes you feel sleepy. [3] This is why you naturally feel more tired at night.

However, research suggests that people with SAD may also experience an overproduction of melatonin. [1] This can further dysregulate any serotonin and melatonin changes.

Disruption to your "body clock"

Our body clock normally uses daylight and darkness to stay aligned with the 24-hour day. During darker months, changes in light exposure can alter melatonin timing and may shift sleep and circadian rhythms. [4] However, people with SAD may have a harder time adjusting to these shifts. [1]

Lack of vitamin D

Known as the "sunshine vitamin", vitamin D is essential for muscle and bone health, as well as a healthy immune system. [5, 6] People with winter-pattern SAD have been found to have lower levels of vitamin D. [7]

Sun exposure is the most effective way to reach your recommended daily intake of vitamin D. [8] However, in Canada, production of vitamin D in the skin falls to near zero for roughly 4-5 months during fall and winter. This raises the risk for vitamin D deficiency. [9]

Health Canada recommends getting vitamin D from food or a supplement every day from ages 2-50, while people aged 51+ should take a 400 IU supplement daily.

What are the risk factors for SAD?

People who live in northern latitudes (like Canada, where winter daylight hours are much shorter, particularly in the far north) have a higher risk of developing SAD. [1,10]

In fact, it's estimated that 15% of the population experience "winter blues", and 2-6% experience SAD (compared to 1% of those who live in Florida). However, it can be difficult to say exactly how many people experience SAD because it can co-occur with other ongoing mental health conditions. [1]

SAD tends to be more common in people with other mental health conditions like anxiety and ADHD, as well as those who live with depression or bipolar disorder, particularly bipolar II disorder. [11]

SAD is diagnosed more often in people assigned female at birth (AFAB), although estimates vary. [1]

The impact of SAD on your health

The mental impact

The exact symptoms of winter-pattern SAD vary from person to person, but may include:

• A range of feelings, from irritability to pessimism, guilt and worthlessness
• Difficulty focusing, remembering or making decisions (also known as "brain fog")
• A constant feeling of sadness, anxiousness or emptiness
• Loss of interest or pleasure in personal hobbies and activities
• Social withdrawal
• Thoughts of suicide or self-harm [11,12]

If you're experiencing severe, persistent symptoms, or any suicidal ideation, help is always available. Call or text 988 to receive support at any time. The Hope for Wellness Helpline is also available to all Indigenous people across Canada: 1-855-242-3310.

The physical impact

SAD doesn't just affect the mind: it can affect the body, too. Symptoms may also include:

• Increased seasonal tiredness and fatigue
• Physical aches or pains, headaches or digestive problems that don't have a clear cause and don't go away with treatment
• Oversleeping (hypersomnia)
• Weight changes [11,12]

Could it be something else?

Feeling tired, low and hungrier than usual in winter doesn't automatically mean you have SAD. Several other conditions cause very similar symptoms. It's worth speaking to a healthcare professional if you're experiencing:

• Ongoing tiredness, weight gain and feeling cold. An underactive thyroid (hypothyroidism) can cause all three, and it's diagnosed with a simple blood test. [13]
• Fatigue, breathlessness or pale skin. Iron deficiency and anaemia are common, particularly in people who menstruate. [14]
• Aches, low mood and frequent illness. Vitamin D deficiency on its own can cause symptoms that overlap with SAD.
• Loud snoring, waking unrefreshed or daytime sleepiness. Sleep apnea is often missed, and it affects mood as well as energy. [15]
• Low mood that doesn't lift in spring. Depression that isn't seasonal needs the same support, but a different plan.

A short appointment and a blood test can rule most of these in or out. If your symptoms turn out to be something else, it’s useful to know early, rather than after a winter of trying to manage it alone.

SAD and weight management

Because it affects both physical and mental health, SAD can have a real impact on our ability to both lose weight and sustain it.

If you're experiencing symptoms like social withdrawal and avoidance, you may find yourself adopting a more sedentary lifestyle. [12]

Other mental symptoms of SAD, like deep feelings of sadness or hopelessness, can also trigger cravings for "comfort foods." These foods are often higher in carbohydrates, sugar, and fat. [12]

When you feel stressed or anxious your body releases cortisol, a stress hormone. In response, your body may crave high-fat and sugary foods because they stimulate your brain's "reward centre". This releases dopamine, the “feel-good hormone”, which provides short-term comfort. [16]

However, repeatedly using food to cope with distress may reinforce emotional-eating habits. [17] What's more, the consumption of these "reward-rich" comfort foods, like refined carbohydrates and sugar, may increase the risk of developing depression and mood disorders. [18]

How is SAD managed?

Help is available to those living with SAD. And, while positive lifestyle changes won’t completely prevent the condition, they may improve your physical and mental wellbeing.

Medical support

If you think you're experiencing SAD, it's important to speak to a trusted healthcare professional. They'll be able to provide you with the right support and resources for your specific needs.

Depending on the severity of your SAD, your physician may prescribe antidepressants like SSRIs (Selective Serotonin Reuptake Inhibitors). These can help treat symptoms of depression by altering serotonin signalling. [19] They may also recommend talking therapies, like cognitive behavioural therapy (CBT).CBT helps you notice unhelpful thought patterns and respond to them differently. There's also a version developed specifically for seasonal depression, sometimes called CBT-SAD. [11] It focuses on two things: challenging the thoughts that show up in winter ("there's no point making plans, it's dark by four"), and gently rebuilding activity through something called “behavioural activation”. That means scheduling small, doable things you'd usually enjoy, even when you don't feel like doing them, rather than waiting until motivation returns.Behavioural activation also matters for another reason. Withdrawing socially is a common sign of SAD, and sometimes the less you do, the less you feel able to do. Planning ahead helps. A standing weekly coffee with a friend takes the decision out of your hands on the days when deciding feels like too much.

There are also several ways to get support if you don't have a regular family doctor:

• Walk-in clinics can assess symptoms, order blood tests and prescribe.
• Virtual care services are available in most provinces, some through provincial health plans and some privately.
• 811 connects you to a registered nurse for health advice in most provinces and territories, free and around the clock. In Quebec it's Info-Santé 811, and in Ontario it's Health811.
• Your local Canadian Mental Health Association (CMHA) branch runs counselling, peer support and referral programs, many of them free.
• Check your workplace benefits. If you have an Employee and Family Assistance Program (EFAP), it usually includes a set number of counselling sessions at no cost to you.

You don't need a diagnosis to reach out. It's fine to start with "I've been feeling low since the clocks changed, and I'd like some help”.

Stay active, even in winter

There's more to physical activity than keeping your body fit. Physical activity is also a great way to boost your mood, and increasing your physical activity may support a long-term improvement in your mental health. [20] This is because physical activity may trigger the release of feel-good brain chemicals like endorphins, dopamine and serotonin. [21] 

The winter months are also a great time to focus on exercises that can be done indoors, like gentle strength training. The good news is you don't necessarily need any specialist equipment, so you can improve your fitness from the comfort of home (try searching for "no equipment home strength training workouts").

Increase your vitamin D intake

Vitamin D deficiency has been linked to SAD. [11] However, when natural sunlight is limited, and a busy work schedule may prevent you from heading outside during daylight hours, there are other ways to reach your recommended daily intake of vitamin D.

While it's still unclear if vitamin D supplementation can help to relieve SAD symptoms, increasing your long-term intake of vitamin D-rich foods may help. [11] Most dietary vitamin D comes from fortified foods, like fortified milk. However, you can also find it in egg yolks and fatty fish like salmon. [22]

And the benefits of vitamin D go way beyond mental wellbeing. As well as increasing your serotonin levels, vitamin D also supports your immune function and immune response, which can help prevent winter colds and other illnesses [23]. Vitamin D also supports calcium absorption, which helps bone health year-round. [22]

Try light therapy

There is evidence to suggest that a lack of sunlight and fatigue go hand-in-hand. [24] But how can you get more sunlight during the darkest months? The answer could sit on your nightstand.

Light therapy uses a light box to mimic natural sunlight. Sitting in front of the light for around 30 minutes during the early morning, between fall and spring, may help regulate your circadian timing and ease the symptoms of SAD. [25, 26, 27]

Look for a light that delivers 10,000 lux of brightness at your preferred sitting distance (you may need to sit closer to smaller lamps to feel the benefits of treatment). [11] It should also be certified as a safe medical device, with no UV light.

However, if you have bipolar disorder, certain eye diseases or take certain medications that increase your sensitivity to sunlight, light therapy may not be suitable for you. If you have any concerns, it's best to check with your family doctor.

Keep a regular sleep schedule

On cold, dark mornings, it can be tempting to spend a little longer in bed. But the best thing you can do for your body clock is to stick to a consistent sleep schedule.

While poor sleep habits can worsen mental health conditions, research has shown that good sleep practices support better physical and mental wellbeing. [28, 29] Try to go to bed at the same time every night, and wake up at the same time each morning, aiming for 7-9 hours of sleep every night.

Conclusion

As winter sets in, it can be all too easy to put a low mood and increased food cravings down to the "winter blues".

It's worth speaking to a healthcare professional if:

• Your low mood has lasted more than two weeks
• It's affecting your work, your relationships or your day-to-day ability to manage
• You've noticed the same pattern two or more winters in a row
• You're using food, alcohol or anything else to cope with how you feel
• The things that usually help aren't helping

You don't need to be at a crisis point to ask for support, and you don't need to wait until spring to see if it passes.

If you're having thoughts of suicide or self-harm, help is available right now. Call or text 988 at any time, from anywhere in Canada. If you or someone else is in immediate danger, call 911 or go to your nearest emergency department.

Darker months may make weight management harder. If you’re looking for additional support, you may be considering if weight loss medication is right for you (subject to an eligibility assessment from a registered clinician). Find out more with MedExpress.

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