Polyphasic sleep is the practice of sleeping in numerous smaller blocks during the day as opposed to sleeping once as is common in many countries. The Siesta (popular in Spain), and Segmented (which was widespread before the advent of artificial lighting) sleep schedules are some of the earlier forms that polyphasic sleep has taken. In recent years, there has been an increased interest in this practice, and many other schedules have been developed with increasing research and experimentation. Sleeping polyphasically can:

• Reduce the total sleep time required.
• Eliminate chronic tiredness.
• Help with insomnia.
• Help many workers cope with their demanding schedules.
• Improve overall sleep quality and quality of life. 

We have discovered certain principles over decades that help predict whether a person can adapt if they are disciplined for at least 1-2 months. Exceptions with long-lasting adaptations do exist, however! Healthy polyphasic sleep:

• Retains a scientifically required amount of SWS, or “deep” sleep (for glymphatic clearing and cell renewal) and REM sleep (for memory and learning).
• Reduces some non-essential light sleep.