https://youtu.be/omw5ldS4R3Y
Bed bugs are attracted to heat and carbon dioxide emitted by us when we go to bed. They mainly feed on the blood of humans but can also use cats and dogs to get their fix. As a rule of thumb (a broadly accurate guide based on experience rather than theory), bed bugs usually feed when it’s dark at night, for their own safety. Of course there is an exception to that rule; bed bugs will come out any time of the day if they are very hungry. Normally, adult bed bugs only feed once a week and females need to feed before they reproduce. But as a young bed bug, called a nymph, when they go through the stages of development (instar stages) they need to feed daily. However, the adults can fast for as long as 60 weeks if conditions are just right. The young bed bug nymphs are a lot more depend on a relatively constant supply of blood. Bed bug nymphs need to feed more often to help complete their life cycle, but again they also can survive without a blood bath for several days. Bed bugs can only survive on blood, unlike most insects that eat a varied diet. Bed bugs are unable to feed on leaked blood rather they need a live host because the blood needs to be at the right temperature and be under pressure. Bed bugs have a limited distance to which they will travel, so roughly speaking, each bedroom or territory will have its own set of bed bugs.
https://www.linkedin.com/pulse/when-do-bed-bugs-bite-randy-bilesky/?published=t
http://www.delta-optimist.com/opinion/blogs/blog-when-do-bed-bugs-bite-1.23152912