The red lines that you may be seeing are called "artifacts". They simply mean that you have lost optimum contact with the sensor and no data was collected during that time. Experimenting with adjusting the sensor will usually find the best spot.
However, there are other conditions that may apply as well.
If a known arrhythmia is present and persistent, it can result in many red lines during the session. This does not mean that you can't use HeartMath. By using the techniques and the breathing pacers in the app, a higher level of Coherence can be obtained. It just means that the emWave program will not be able to calculate the coherence scores accurately. Inner Balance will manifest this loss of signal differently. It displays as blank spots in the tracing.
When the sensor is attached to the USB Module or the emWave2, please try adjusting the sensor where it goes into the device; i.e. ensuring that the post is all the way in, perhaps turning it slightly as you use it to see if the signal improves. If it does, this could be a contact problem; please contact HeartMathTech Support.
If your extremities (hand or ear) are cold, reduced circulation may interfere with recording an accurate pulse signal and affect the data collection process. Warm your ear lobes by rubbing them gently.
Please Note: It does take a while for the body to fully warm up and the extremities to regain their normal blood flow. Exposure to cold increases the affinity of adrenoceptors for norepinephrine. This results in a constriction of the blood vessels and a reduction of blood flow to extremities. The ears may be warm but the circulatory system has to be fully warmed up and that can take time. They need to warm up to the point that their hands and feet are getting blood flow and feeling warm too.
For your hands, either rub your hands together rapidly to warm them up, or run them under warm water, ensuring to dry them thoroughly, and then check the shape of the pulse wave in the heart rhythm recording mode to see if the signal has improved.
You may have to search for the optimum spot on your ear lobe or even switch to the other ear lobe. As human beings we're not the same on both sides of our bodies and you may get a better reading by switching to the other ear lobe.
The sensor strap can't be too loose or too tight. Position your finger tip so that the fleshy part of your finger is directly over the little window on the sensor and you should see the red lines disappear.
Insert your fingertip into the finger sensor. Make sure that the fingertip is over the small rectangle in the finger sensor - if the finger joint is over this rectangle or the tip of the finger is too far back data quality will be diminished. Adjust the strap to be comfortably snug. Again, too tight or too loose will affect data quality - you can get a sense for the proper pressure by starting to collect data with the pulse wave displayed then pressing down and lifting the finger in the sensor to see what happens to the pulse wave- it will flatten out when there's too much or too little pressure.
The hand and finger in the sensor, should be in a relaxed position and on a hard flat surface to minimize movement which can result in red-line artifacts in the HRV graph.