A good night's rest is important for everyone. But, when symptoms of depression, mania, and/or anxiety are prominent, sleep often is disrupted.
Of course there are many medications available to assist with sleep. But, there are also behavioral changes you can make which can help improve your sleep.
First, don't watch the clock or check your phone. This tends to only increase anxiety.
Second, try to stick to a regular bed time and wake time, even on weekends.
Third, routine, routine, routine. Whether it's a warm shower followed by a cup of non-caffeinated tea, or reading in bed for 30 minutes, find something ideally with lower light, and stick to it. Brighter lights, such as from a smart phone aren't helpful. You want your brain to learn this is time to settle down.
Fourth, no naps. Especially in the later part of the day.
Fifth, exercise is good for sleep (and mood, and anxiety).
Sixth, alcohol is not your friend. Alcohol actually keeps you from getting the most restorative sleep.
Seventh, if you're awake and can't seem to go back to sleep, you can tell yourself you're just resting and enjoy your comfy bed. If you need to get up, do something that is dark (no bright screens), and quiet and relaxing until you're tired enough to go back to bed. Try to not nap the next day.
Last, keep some kind of sleep record--what you did during the day, did you exercise, did you have a big meal just before dinner, did you have sex before bed, did you take all your medication(s), had caffeine, etc. Look for patterns and then share these with your provider.
Over time, these suggestions should prove beneficial for improving sleep, and hopefully improve mood and reduce anxiety, as well.