Sources: National Sleep Foundation @ https://www.sleepfoundation.org/, and https://pubmed.ncbi.nlm.nih.gov/29073412/

Assuming you're a healthy individual in the 18-to-64 age range with no evidence of a sleep disorder, you should ensure that you're allowing yourself at least eight hours per night.

Start there as your initial goal or starting point, then after a couple of weeks ask yourself these questions:

• Have you been trying to get the full eight hours, but failing?
• Do you need more sleep to get going and feel productive, healthy and happy?
• Do you have health issues such as being overweight? Are you at risk for any disease?
• Are you experiencing any sleep problems?
• Do you need caffeine to get you through the day? 
• Do you ever feel sleepy when driving?
  
• Is your line of work or daily activity level particulalry energy-intensive?
  
• If you're unconstrained by work or your alarm clock, do you sleep for significantly longer than usual?
  

If you answer ‘yes’ to any of these, consider aiming for more sleep.

Track and adjust

Your own perfect sleep amount will be determined by many factors, including your overall health and activity levels. The best way to land on your optimal amount is to track and adjust as necessary.

Most of the damage that under-sleeping can wreak on your mind, body, and spirit becomes evident at around six hours per night or less. So begin by aiming for eight hours, but it’s probably OK if you work your way back towards seven hours.

However you should also be open to moving the other direction, out to nine hours or even more per night, if that’s what your body is telling you it needs.