
In total disagreement with Golden Lady - if you try and treat all dogs in a multi dog household as equal you can cause some problems, because they are NOT all equal, they are different ages, breeds and temperaments.
I dont think thats really the problem though but do look at where htey all fit in with one another, who is a fair 'boss' and who is not sure of his place etc.
Trying to change the heirarchy between dogs is difficult and potentially can cause more problems (if you get it wrong and try to promote a nervous submissive dog over a confident dominant one for example) - get it RIGHT though and it can well make life a whole lot easier, making it clearer for each dog where they stand.
I find a huge number of problems are caused by people trying to keep all dogs totally equal, or, trying to promote one above the other based on some human concept that dogs dont follow, such as 'she was here first' or 'hes the biggest'.
Preventing any misunderstandings such as being woken by a grumbley dog, is a great start, them each having their own place to sleep should help too.
I cant say what else could be adding to your dogs anxiety but you need to look at his and your life as a whole, rather than one specific incident.
One thing I have found that really can help underconfident dogs is clicker training. There isnt a specific thing you clicker train them to do, its more that the process of learning this way builds confidence. You will know yourself, when you figure out how to do something, an answer to something, how something works, for yourself.. you get a great deal of confidence out of that. Far more so than if someone gives you the answer or does the thing for you.
Think also about your role in your dogs life, and think about the relationships you have had with people who have taught you a lot and built up your confidence. Possibly a parent or grandparent or aunt/uncle or a teacher - that kind of relationship is the one you want with your dog, thats what will foster more confidence and reduce anxiety.
Golden Lady - where DO you get your ideas from? Treat them all exactly equally?
So, I'm to treat my uber sensitive needy male collie x who is 4, EXACTLY the same as my bolshy ratbag of a 10 month old deerhound bitch? And both of them exactly like my 8 year old staffie x boy.. and all three of those like my reactive paranoid bedlington x whippet lad (5), and all four of THEM, just the same as i treat my 13 year old saluki girl...
I cant, theres just no way that would work, or be kind, or effective.
My old saluki girl needs limited exercise, a quiet sensitive tone of voice, gentle pootles round the block and a treat at bedtime.... if i give that to my staffie lad who needs loads of mental challenges during the day, hours of exercise and a firm, assertive tone of voice, he would be horribly unhappy, bored and misbehave.
If i treat her hte same as i treat him she would collapse through over exercise, be terrified of me and be miserable.
There is no way i could treat all five of my dogs identically, each one is a different personality, each one has different needs, desires, ways of learning.
To suggest that one must treat all dogs identically is quite frankly ridiculous... and potentially very dangerous if some one were to take you at your word - if i tried to promote a submissive dog to the same level as a dominant bitch.. i could have serious bloodshed on my hands, that would be stupid meddling in a thing that requires no interferance from me!