Employees should also be encouraged to continue their normal self-care activities, such as getting enough sleep and exercising. To help with this effort, maintain a healthy office to keep employees at the top of their game. Although it's tempting to give in to holiday indulgences, healthy snacks, stretch breaks, or walks during the day can have a marked effect on morale and reduce stress.

Create a stigma-free workplace

Too often, we forget the power of language. In order to create a stigma-free environment, employers would do well to pay attention to the words they use to describe stress and responsibilities. Phrases like, "this is a crazy time of year" or "I'm losing my mind" are invalidating to employees who may have a diagnosed mental health condition and reinforce the stigma that conversations about mental health are discouraged.

Instead, companies and managers should create opportunities for dialogue among employees about mental health and model a positive culture. For instance, encouraging senior leaders to share their own struggles and strategies for managing stress can have a ripple-effect on the entire workforce. These leaders often have a platform and the respect of their teams, and their honesty may be the push struggling employees need to open up and seek help.

Senior leaders should also be trained to "Know the Five Signs" of emotional suffering and be equipped to step in when needed. To that end, workplace mental health training programs can be invaluable. For example, the Mental Health First Aid program trains employees to recognize and respond to a mental health problem or crisis. Leaders should be on the lookout for indicators of when offering support is important, such as changes in personality (behaving erratically, withdrawn, short-tempered, seeming emotionally distant, agitated, or nervous) or neglecting self-care.

Highlight available resources

If employees do need support, leaders and teammates should feel empowered to direct them to available resources. In addition to traditional, in-person counseling, there are many digital resources available to maintain resiliency and address mental health concerns. For instance, services like AbleTo offer customizable online counseling with a live therapist for one-on-one support. Similarly, employees who are interested in daily support with mindfulness may like the Calm or Headspace apps, which provide guided meditations and other resources to help manage stress and anxiety.

Occasionally, there may be situations where companies will require longer-term assistance for at-risk employees. In these cases, companies should consider turning to resources designed to maintain a safe and healthy work environment, such as Aetna's Organizational Risk Management Center (ORMC). This group works directly with HR functions and managers to help employees in need by connecting them with appropriate resources such as counselors, telephonic support, and trauma and coping resources.

Lastly, because maintaining mental health is a year-round effort, it's important to continue promoting resources and engaging with employees regularly about mental health. Opportunities for team dialogues about mental health can be scheduled monthly or quarterly to assess employee morale and address any company issues which may be causing unnecessary stress. If employees realize that their company values their individual happiness and success, they will feel more supported and encouraged to open up about mental health concerns with their colleagues.

Although the holiday season is a time to celebrate with family and friends, it can also be one of the most stressful times of the year. However, by setting realistic expectations for employees, encouraging a dialogue about mental health, and promoting available resources, employers can support their employees' mental well-being and set them up for success in the new year.

Cara McNulty, DPA is president of Aetna Behavioral Health.

Read more: 

• Employee stress spurs employer spending on pricey well-being perks
• Top 10 ways employees like to de-stress after work
• Supporting employees through the holidays (and beyond)