Hypothyroid people often compensate for the low cellular energy by increasing the stress hormones (adrenaline and cortisol). The stress hormones can keep the body temperature and pulse rate artificially up. Often the stress hormones are high in the morning before eating breakfast.
Sometimes the adrenaline is up to 40 times higher in a hypothyroid person compared to a person with good thyroid function, this leads to a very high pulse rate, which can create problems with falling asleep and waking up during the night. The high adrenaline also tends to cause cold hands, feet, and nose.
If the stress hormones are high, there will be a drop in temperature and pulse rate to the hypothyroid level after breakfast, as the stress hormones are allowed to normalize, with the increased blood sugar.
By measuring the temperature and pulse rate before and after breakfast, it is possible to separate the effect of the stress hormones from the actual thyroid function.