THE BLOG
01/11/2013 01:11 pm ET Updated Mar 13, 2013

Winter Blues and How to Make New Year's Resolutions Stick

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If you're like many of us mortals, by the end of January you've already begun to break those promises that seemed so manageable just a few weeks earlier. By the end of the first week in January, an estimated 25 percent of the well-intentioned will have broken their resolutions; by the end of January, one-third will have lapsed; and by July, more than half have lost their resolve.

Why do we seem so incapable of accomplishing a goal that we set for ourselves and truly desire? Part of the answer has to do with timing. Winter is not an ideal season to successfully execute big changes.

The celebration of the New Year on January 1 is a relatively recent phenomenon. For thousands of years the beginning of the year was defined by the vernal equinox and celebrated in mid-March. Spring provided a natural marker of the annual beginning of plant and animal life.

The Romans shifted New Year to January, the beginning of their civil year, when their leaders took power. (The month of January took its name from the Roman God of beginnings, endings and transitions, Janus, a two-faced deity, one face looking forward into the future and one looking back at the past.)

This new and wholly man-made order represents an early example of the notion that we humans exist outside nature's rhythms, that we can create our own rhythms with impunity. And we continue to learn there's a price for such hubris.

Our species evolved on the equator and our genome is adapted to that environment. Equatorial life is characterized by days and nights of equal duration throughout the year.

We have learned that our physiology is exquisitely entrained to this balance. This external condition was internalized. We have a biological clock in every cell in our body that is cued by the daily dance of light and dark.

This circadian system coordinates the daily increases and decreases in the production of hormones and neurotransmitters. Most essential biological functions (mood regulation, energy level, fertility, immune function, sleep, appetite, concentration, and metabolism, to name a few) are dependent upon this light-dark cycle.

As we migrated out of our African homelands and settled in areas that experience dramatic seasonal variation in sunlight, that all changed.

If we are wired for optimal function at the equator, what's the big deal about moving to New York City in terms of daylight? Well, there is essentially no variation in hours of daylight at the equator. In 2012, New York City enjoyed 15 hours and six minutes of daylight on June 23, and nine hours and fifteen minutes of rays on December 23. That's a six-hour difference, 50 percent of an equatorial day. Change a powerful biological variable that much and you're talking about a completely different ball game. If you decreased the oxygen content in the air we breathe by 50 percent, we'd be extinct.

A growing literature documents the consequences of the winter loss of light in temperate climates. Perhaps the most familiar winter syndrome is seasonal affective disorder, aptly abbreviated SAD. Individuals with SAD experience a significant dip in mood as the days grow shorter and by winter are in a depressed state. Their mood begins to lift in spring, and the depression is usually fully resolved by summer. This pattern repeats itself year after year. Mood is not the only casualty. Typically, SAD triggers an increase in appetite, specifically a craving for sweets and carbohydrates, that is associated with weight gain. Despite the spring recovery from depression, that winter weight often proves difficult to shed. The symptom profile also commonly includes increased sleep, fatigue, anxiety, lower self-esteem, and irritability. Distance from the equator dictates prevalence rates that range from 1 to 2 percent in Florida to approximately 10 percent in New Hampshire, and peak during the months of December, January and February.

While these numbers may not be extraordinary, the prevalence of what's called "subsyndromal SAD" is remarkably high, affecting a quarter to a third of the population in northern climes. This category is simply a milder form of SAD, where individuals do not meet criteria for a clinical depression but experience significant seasonal variation in mood. Here's a list of the most common winter signs:

• Decreased energy, lethargy, often tired
• Decreased efficiency and concentration, indecisiveness
• Increased difficulty completing tasks
• Mood less buoyant
• Increased appetite and sweet craving
• Self-esteem not at its best

Sound familiar?

Given what we've learned about the impact of sunlight on our physiology, it is not surprising that most of us experience some degree of mood seasonality. And while it may not constitute a disorder that requires medical intervention, it certainly compromises our ability to function at our best.

So why have we assigned one of our culture's hardest tasks, New Year's resolutions, smack in the middle of this time when we're at our worst?

What are the chances of successfully assessing your life, identifying something that needs to change, and marshaling the resolve to act on that promise to yourself, when you feel a bit down, low-energy, indecisive, overweight, and less confident than usual?

When put this way, it seems amazing anyone succeeds at the New Year's resolution games. The good news is we've learned a lot about the biology of these seasonal changes and how they affect a variety of brain functions. This knowledge has translated into techniques that can dramatically up your chances of sticking with a plan to make an important change in your life.

The two biggest players are serotonin, a neurotransmitter (neurochemical messenger), and brain-derived neurotrophic factor (BDNF), a regulatory tonic for the brain. Low serotonin levels are thought to be a common contributor to depression, and most antidepressants boost the serotonin system. Low BDNF has also been implicated in depression as well as impaired cognitive functions such as learning and memory. Here's the kicker. Both serotonin and BDNF show strong seasonal variation with significant dips in months with decreased sunlight. When these two systems are not functioning well, our capacity to regulate mood, energy, decision-making, and the acquisition of new data (everything you need to formulate and fulfill a New Year's resolution) is impaired.

And guess what boosts both these agents most? Yup, exercise. And by exercise, I mean anything that gets you up and moving every day. That's right, every day!

But there's much more to optimizing your chances of follow-through at this time of year. Here's a list of pointers drawn from the research world.

1. Exercise: actually increases the size and integration of the prefrontal cortex, the part of your brain involved in delayed gratification

2. Sleep: We think better, and improve our ability to delay gratification when rested. Oh, and by the way, a common research model for sleep deprivation is anything under six hours!

3. Meditation: Ten to 15 minutes per day decreases slips by helping to inhibit brain centers involved in impulsive behavior.

4. Diet: Spikes in blood sugar levels impair prefrontal cortex function in rats -- so low-glycemic and mainly plant-based diets work best

5. Forgive Yourself: Slips are a normal part of making changes. They are temporary setbacks and should not be seen as losing the battle. Research has shown that guilty feelings after slips worsen future tests of willpower. Guilt actually puts us in a biology that activates impulsive brain activity.

6. Plan for the slip: Do a post-mortem on the slip. When, where, with whom, feelings... Then try to safeguard yourself from identified risks. And forgive yourself!

7. Befriend your future self: Part of the reason we're so bad at making changes now that yield benefits in the future is because we're not connected to our future self. They even have a term for this phenomenon, delay discounting. Offer people $5 now or $10 in a month, they take the immediate gratification. Some recommend writing a letter from your future self to your current self and describe you doing something in the future. Such exercises repeatedly show increases in retirement savings, healthy behaviors, and debt resolution.

For more by Paul Spector, M.D., click here.

For more on success and motivation, click here.

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