I like chat programs used as email - that is, non-real-time. I have lowered my anxiety a lot by realizing that texts are not realtime in my life 98% of the time, and to treat them accordingly: Checked on upon occasion. Don't stress about whether the person on the other end will be upset if you don't get back right away.
Planning something? Need someone right away? Set the expectation of response beforehand or just call them.