We have ALL been there. When you send a message to someone you like, they have their stupid read receipts on and they don't respond. Now a rational person who doesn't suffer from anxiety will realise that life gets in the way. Maybe they can't respond right now, maybe they are working or with family or even at a funeral and they just don't have the actual time to respond.
A person with anxiety can't deal with this, especially when you see the "…typing" and then it disappears and they don't respond for hours or even days. Firstly let's address the hours. If a person has read your message and they have not responded in a few hours, STOP freaking out. It has only been a few hours.
The best thing for you to do when this happens is to find something else to do. Exercise, knit, go for a drive, cook, or see a friend…whatever is going to take your mind off that message and the stupid read receipt.
Now one thing that really irritates me and my anxiety is when they have read the message on social media and for the next few hours, it still says they are active. Nothing more boils my blood than the fact that they have had their phone in their hand and didn't have the decency to respond…THAT is my anxiety trying to drive me crazy…and sometimes it works. Even when you sent a text message and it says read, they don't respond and then you see them on social media…so your anxiety will kick in again and convince you that you aren't important enough to respond to, or that he doesn't like you, etc. This is just nonsense. You're not crazy, you just suffer from a mental illness and you need to embrace that but not let it rule the way you live your life.
I have made the mistake of sending multiple messages because my anxiety has reared its ugly head and made me believe that this person is deliberately ignoring me. Where you are in your relationship with that person is really important. If it is the beginning, distract yourself and put your phone away. Don't touch it because the more you touch it the more you will keep visiting that message and the more your mind will play tricks on you. GO AND WATCH A MOVIE, do something that has nothing to do with your phone at all.
If you are really invested in this person and they haven't responded to your message in a few hours, you should already know how to deal with it, but some people don't and they end up sabotaging something that could be really good for them.
Now let's address when they haven't responded in a couple of days. THAT is a red flag. In today's day and age, people having their phones on them is almost as often as they blink. There are certain generations who don't adhere to this new common experience. However, they are very few.
If someone hasn't responded to your message in a couple of days chances are there is something wrong and you have the right to panic. 24 hours is fine. You don't know what is happening in their lives, but if it gets to day 3 and beyond, I would start asking yourself why they aren't responding and better yet, maybe even send them a light-hearted message like "Are you still alive? I'm about to send out a search party haha" If they read that and don't respond within a few hours then you know that something is wrong and you need to look at whether you want to put yourself through any more anguish.
For those of you out there battling your anxiety, remember that anxiety is not your friend. You have to live through it so obviously, you need to find coping mechanisms, but don't put yourself through any more stress than you deserve and if people aren't respectful enough to respond in a couple of hours to a day…maybe it's time to look at whether they deserve YOUR time and energy rather than chasing theirs…especially if it is a pattern.