Are you experiencing abrupt awakenings at night?
Do you have unexplained urinary incontinence during the night?
Do you have good sleep hygiene?
How many hours of sleep you get per night?
Do you find hard to fall asleep?
Do you take some medications?
Are you aware of other sleep disorders you may have it?
Do you feel excessive daytime sleepiness?

It the weirds thing isn't it!!!! I spent years doing that but all of a sudden I stopped. Now I have bigger problems with my sleeping habits lol.
I can remember it quite clearly though. I use to actually find it comfortable to sleep with my arm up in the air. Until I would leave it up there for hours and it was so numb it would hurt.
Let me know if you find any answers.

What sleep disorders you have now?
Can you think of other medical problems you had when you were experiencing sleeping with the arm up in the air?

Sleep Paralysis, eating in my sleep, Just had a sleep study done to rule out sleep apnea coz I wake up choking sometimes.

The Sleep Paralysis and choking were happening when i had floating arms.

Have you done a sleep study at sleep specialist's office?
Did you get some medical explanations about sleeping with your arms up?
I had experienced sleep paralysis myself 15 years ago, but it went away after couple of months and never appeared again.

Are you experiencing daytime sleepiness?
Do you have headaches, sore throat, or dry mouth in the mornings after waking up?

Yea, the study was done at a specialist clinic. i really hope they get some answers because it was very uncomfortable and i had a rough broken sleep.

I have experienced SP for as long as i can remember. As wells as reoccuring dreams and nightmares, choking in my sleep, sleep walking and talking.

I am always tired. And sleep any chance i can during the day.
I am on medication for hashimotos disease, depression, and anemia. All these things seem to be under control by the meds, but i am still so so tired.

All of the conditions you are suffering from (anemia, Hashimoto's, depression) together with sleeping problems, can be a reason for feeling tired all the time.
I found some informations about a case control study on psychiatric disorders in Hashimoto disease, that indicates an association between the presence of a lifetime diagnosis of mood or anxiety disorder and sleep disturbance and high levels of thyroid autoantibodies in Hashimoto's disease patients, independently of impairment of thyroid function.
Your anemia, depression, sleeping problems, fatigue and weakness can be treated as a part or symptoms of one condition know as celiac disease.
Do you usually have gas, mild stomach pain, abdominal swelling and bloating?
Are you experiencing abnormal stools?
Do you suffer from frequent respiratory infections?

Sorry to hear about that. I know it sounds silly, but have you tried to restrain yourself when sleeping?

Hello redshoes, I am sorry to hear your sleep is not going so well. I had the same experience for many years, sleeping with my arm up in the air, actually I found it very comfortable although rather chilly. No matter how often my Mom tucked my arm in, up it popped again. I read in later life that this is something that is practised as a yogic exercise, amongst the Hindi yogis in India, controlling one's limbs during sleep as a mind practice. They would seek very hard to fall asleep with an arm up or less often a leg. You might not believe in reincarnation but funnily enough this settled me in my own mind. I wish you all the best, anyway.