“The best way to understand how grief can affect your health is to understand what bereavement entails: one, a major stressor; and two, loss of a close relationship,” says M. Katherine Shear, MD, professor of psychiatry at Columbia University and director of the Center for Complicated Grief. “Close relationships help regulate our daily psychological and physical functioning,” explains Dr. Shear. “Their loss…typically leaves people feeling out of control and disoriented.”

Grief and Exhaustion

One of the most common early symptoms of grief is extreme tiredness that makes even routine tasks difficult. “I had no idea that grief would be physically exhausting,” says Anna Whiston-Donaldson, whose 12-year-old son Jack drowned in 2011. “My body felt fragile and very tired.” In her book Surviving Grief … and Learning to Live Again, psychologist Catherine M. Sanders, PhD, writes that the bereaved can “become so weak that we actually feel like we have the flu…[and] this weakness frightens and perplexes us.”

Difficulty Thinking Clearly

Cognitive effects of grief “can interfere with the ability to think clearly, to make decisions and judgments, and problem solve,” Shear says. Studies have associated bereavement with poorer memory performance and trouble concentrating.

Sense of Being Alone

Grief is often accompanied by feelings of loneliness or isolation. Intrusive thoughts about one’s loss “can be debilitating and make a person feel like they’re not connected to the world or anyone around them,” says traumatic grief counselor Joanne Cacciatore, PhD, associate professor of social work at Arizona State University. People with prolonged grief disorder, also known as complicated grief, may experience “frequent insistent thoughts of the person who died, a sense of disbelief and difficulty feeling connected to other people…and a range of difficulties related to emotion regulation,” Shear says.

Depression and Substance Abuse

According to Mental Health America, a national advocacy group, prolonged grief can trigger anxiety attacks and depression. Research has found that about a quarter of people who lose their spouse experience clinical depression and anxiety in the first year. Bereavement has been associated with substance abuse, and research published in Substance Abuse Treatment, Prevention, and Policy specifically found a greater risk of alcohol-related problems among bereaved men.

Heart Health and Immunity

The emotional impact of grief is often described as “heartache” or “heartbreak,” but the release of stress hormones associated with grief can cause actual cardiac problems. “We know a fair amount about how stress affects the cardiovascular and immune systems, namely by activating both, and in vulnerable people this leads to increased rates of cardiovascular disease and cancer,” Shear says. “Acute stress can also cause something called stress cardiomyopathy, which is an acute form of cardiac illness.” One study found that the incidence of an acute heart attack increases 21-fold within 24 hours of the death of a loved one, before declining steadily with each subsequent day. In another study, British researchers found that older people who are grieving are more likely to have weakened immune systems and develop infections.

Coping and Treatment

While potential health consequences related to grieving are a serious concern, Shear stresses that grief itself should not be treated as an illness. “Grief is the natural response to loss and when we lose someone we love, the loss is permanent and impactful, and grief is also permanent,” she says. “No one really gets over an important loss. Grief counselors often talk about positive outcome as finding a ‘new normal.’ ” Dr. Cacciatore stresses the importance of self-care. “A person needs to take good care of themselves and their grief,” she says. “Sometimes remembering things as simple as eating well and drinking water can improve a person’s quality of life. Even getting 20 minutes of sunshine outside can help.” RELATED: Managing Grief After the Death of a Loved One A grief specialist, whether it’s a psychologist or a counselor, can help a bereaved person cope with their emotional and physical symptoms. “It provides a safe place for people to be with their grief and to remember their dead without others pressuring them to be okay,” Cacciatore says. One of the ways Whiston-Donaldson, 44, copes with her continuing grief is by writing about it on her blog. “My coping methods have been writing, letting myself feel my feelings, and connecting with others who are hurting,” she says. Shear agrees that sharing and connecting with others is key to finding that new normal following a loss. “We do not grieve well alone,” she says. “Part of the natural adaptive process involves reconnecting with others.”