What sleep cycle should I adopt to sleep as little as possible with no cognitive function decline?
I think it would be hard to tell an exact number of sleep hours required to prevent cognitive decline, it is probably different for everyone and dependent on you risk factors. Cognitive decline can have many causes and contributing factors: genetics, inflammation, health problems, normal aging, substances, etc. If you are referring to Alzheimer’s your biggest risk factor would probably be genetics, ie if you have someone in your family that was diagnosed with Alzheimer’s and they had a specific gene variation that contributed to the development, you have a higher chance of getting dementia. Other risk factors include diabetes, depression, chronic head injuries, hearing loss, high alcohol use, high benzodiazepine use, obesity, diet and plain old aging. It is also just random.
Chronic sleep deprivation would probably make these worse if you have a lot of these risk factors, so it would probably make sense to prioritize getting good sleep, along with working on the other factors.
There is no perfect amount of sleep to get, it is about getting high quality sleep. The American Academy of Sleep Medicine recommends 7–9 hours for adults, but also says some people only need 6 and others only need 10. I’ve heard some of my clients who have gotten off benzodiazepines or sleeping pills say that “5 hour of med free sleep is more restoring than 8 hours of Ambien and/or Klonopin sleep”. And it goes without saying that 5 hours of apnea free sleep is better than 10+ hours of apnea filled sleep.
Sleep and cognitive health is about understanding your personal risk factors and gently improving and working on what is in your control. The key is prioritizing sleep and your help, rather than a prescription for an amount of sleep. If you work on understanding your own sleep and health barriers and fixing them, you can drastically improve your sleep and cognitive health and decrease your chances of cognitive decline.
This answer is not a substitute for professional medical advice. This answer is for general informational purposes only and is not a substitute for professional medical advice. If you think you may have a medical emergency, call your doctor or (in the United States) 911 immediately. Always seek the advice of your doctor before starting or changing treatment. Quora users who provide responses to health-related questions are intended third party beneficiaries with certain rights under Quora's Terms of Service (http://www.quora.com/about/tos).