My sleep is interrupted every hour or so resulting in about 4 hours of "sleep" at night, inability to return to sleep at around 3 am and impaired daytime functioning. Reading Matthew Walker's "Why We Sleep" about the long term effects of inadequate sleep is very discouraging.
Do you know what prevents you from sleeping? Anything help?

I used to have a lot of trouble sleeping but got diagnosed with sleep apnea and with CPAP , I sleep much better! Make sure that there is nothing physically wrong that could be causing sleep disturbance. It is also very important to develop good habits around sleep time. No technology, etc.
I hope this may be helpful to you but I wish you well and good sleep.