After the holiday lights and decorations come down, the reality of a long winter ahead sets in. Even for people who like winter, the season's shorter days and colder temps can take a toll on senior mental health. When that happens, keeping a positive outlook is crucial to staving off the winter blues.

There's even a name for feeling down when long summer days are gone: Seasonal Affective Disorder (SAD). SAD is a type of depression that sets in as days shorten in the fall, and it can worsen over the winter months. But you can take steps to beat the winter blues, keeping your mind and body fit until spring lifts your mood again.

Here are five ways to improve senior mental health during the winter.

Boost Your Mood with Exercise

Going to the gym in the winter is a great way to improve mood, get out of the house, meet new people and feel a sense of purpose. That's because physical exercise brings a rush of "feel-good" endorphins that can make you more optimistic and upbeat in the winter. Physical activity can also lower your risk for heart disease, keep your blood pressure in check and help manage diabetes and other chronic medical conditions.

The American Heart Association recommends getting 150 minutes (2.5 hours) of cardiovascular activity per week. You can hit that mark with just a 30-minute walk, five days a week. Enlist a friend to walk with you, and you'll get bonus mental health benefits from social engagement. If you don't have a gym membership, you can also work out with online cardio, yoga, Zumba and other fitness workouts you can do from home.

Practice Gratitude

Research shows that gratitude is "strongly and consistently" linked with greater happiness, according to Harvard Health. Feeling grateful for the good in your life can help you feel more positive, appreciate each day's experiences, build stronger relationships and maintain senior mental health. Make it a practice to write down five to ten things you're grateful for each morning. You'll start the day with a more positive attitude and become more aware of all the good things in your life and relationships.

Bask in More Light

Getting less sunlight due to shorter days can lead to low energy, difficulty sleeping, carbohydrate cravings that lead to weight gain and a less positive outlook. One way to replace summer sunshine is to sit in front of a light therapy box every morning. The light therapy box exposes you to bright, artificial light that can boost your mood for the day and improve senior mental health. You can also get more sunlight by going outside during the day. Take a walk on a sunny day for an endorphin mood boost combined with sunlight exposure. Just make sure you wear sunscreen to protect your skin from harmful UV rays.

Get Enough Sleep

Getting enough sleep each night can help maintain senior mental health. Without adequate sleep, you're at greater risk for depression, anxiety and irritability, according to the National Institutes of Health. On the other hand, getting a good night's sleep improves learning, creativity, problem-solving skills and control over your emotions and behavior. But the positive effects of getting enough sleep every night don't stop with senior mental health. Getting enough sleep is also vital to good physical health since sleep supports healthy brain function and decreases your risk for heart disease, kidney disease, high blood pressure, diabetes and stroke.

Take an Online class

When you're intellectually active, your brain benefits, potentially improving memory and thinking ability. Why not take advantage of more indoor time during the winter by taking an online course? Harvard University, University of California, Berkeley, Boston University and other universities offer free online courses on a large variety of topics. Classes include history, business, financial literacy, psychology, art and many other fields.

Kick off your winter learning experience with "The Science of Happiness," a course from Berkley University of California focused on science-based principles and practices for a happier and more meaningful life. You can do an online search for free online courses or browse free university courses at edX, an online education platform.

Take Your Positive Attitude Forward

Now that you know five ways to beat the winter blues, customize this with your own ideas to help you feel more positive and optimistic this winter. Then continue with your new mental health habits when spring returns for better senior mental health overall.