Air conditioners feel great when the weather turns hot and sticky. Most of us spend hours under one, at home, at work, or even on long drives, and it barely crosses our minds. But sitting in cold air for too long can quietly leave your neck and back feeling tight and sore. AC isn't going to cause a serious spine problem on its own, but it can tighten up your muscles and make existing pain worse.Why Does This Happen?Muscles function optimally when they are relaxed and warm. As soon as the cold air comes into contact with them, the body automatically starts tightening them as it seeks to retain its warmth. When this occurs in places such as the neck, shoulders, and lower back regions, there is a chance that these muscles will get sore and stiff. This condition worsens even more if the cold air continues to blow in the same spot for hours, especially while sleeping or sitting at a workstation.What It Does To Your Neck And BackYour neck and back rely on several muscles to keep you upright and moving properly all day. Cold air can slow blood flow to these muscles, which makes them tense up more easily. That's why people often wake up with a stiff neck after sleeping under an AC vent or feel upper back pain after a day in a freezing office. If you already deal with something like cervical spondylitis or chronic back pain, cold air can make those symptoms flare up even more.It's Not Just The ACCold air rarely works alone. Bad posture, sitting too long, skipping exercise, and not stretching enough all add to the problem. Picture sitting at a computer for hours in a chilly office: that's tense muscles and poor posture combining at the same time, which makes stiffness and pain even more likely.Simple Ways To Avoid ItA few small changes can make a real difference: keep the airflow away from your neck and back, set the temperature to something comfortable rather than freezing, get up and stretch every so often, drink enough water, and keep a light sweater or shawl nearby if it gets too cold.AC keeps us comfortable when it's hot outside, but too much cold air for too long can leave your neck and back stiff and achy. A little attention to airflow, posture, and movement throughout the day can help you stay comfortable without paying for it later.(By Dr. Aanchal Sharma, Pain Physician, Principal Consultant and Head of Department, Department of Pain Medicine at BLK MAX Hospital, New Delhi)