IMO I don't think a dog should be locked up that long without human companionship. I also keep my dogs in the kitchen when I am not present to watch them.
It is important to realize that dogs with separation anxiety are not doing these things to get even with the owner for leaving, out of boredom, or due to lack of obedience training. These dogs are not being destructive out of “spite” or “anger.” They are truly distressed when left behind.
The first step in treating separation anxiety is to break the cycle of anxiety. Every time a dog with separation anxiety becomes anxious when its owner leaves, the distress she feels is reinforced until she becomes absolutely frantic every time she is left alone.
Owners should give the dog an acceptable item to chew, such as a long lasting food treat only when they go out. The goal is to have the dog associate this special treat with the owner's departure. Treats might include hollow bones stuffed with peanut butter or soft cheese, drilled out nylon bones or hollow rubber chew toys such as Kong toys similarly enhanced (place in the freezer before giving it to the dog to make it last longer). Give the bone to the dog about 15 minutes before preparing to depart. The chew toy should be used only as a reward to offset the anxiety triggered by the owner’s departure. Hiding a variety of these delectable food treats throughout the house may occupy the dog so that the owner’s departure is less stressful.
Your dog should not be allowed to sleep in bed with you as this only fosters dependence. In fact, it is best if your dog is not even allowed to sleep in your bedroom. First, you need to train your dog to sleep in her own bed on the floor in your bedroom. She may have to be taken to her bed several times before she gets the message that you really want her to sleep in her own bed.
Seperation anxiety us usually caused by the dog being used to someone being around all of the time, giving the dog a lot of attention, or trama when no one was present in the past.
HTH