Can it be used at night without tubelight?

Since infrared radiation is emitted by all objects with a temperature above absolute zero according to the black body radiation law, thermography makes it possible to see one’s environment with or without visible illumination.

What is the importance of monitoring the Vital Signs?

The recording of the vital signs i.e. pulse rate, body temperature, respiration rate and blood pressure are very important for monitoring the physical health condition of a person as abnormal variations in these parameters may result in severe illness. Abnormalities in body temperature may be due to fever, infection, stress, dehydration etc. Serious health issues like atherosclerosis, heart failure, stroke, hypertension etc. may result due to high blood pressure. Pulse rate, which denotes the number of times heart beats in one minute duration, is another important parameter. The heart rate needs to be in control as an increase in pulse rate is an indication of stress, anxiety, thyroid disorder, shock, anemia etc. Finally, a proper check on respiration rate i.e. number of breaths per minute is necessary to keep a check on breathing problems like asthma, hyper or hypoventilation, respiratory alkalosis, apnea and also other problems like anxiety, pneumonia, congestive heart failure, lung disease, use of narcotics, or drug overdose.