Human sleeping pattern has several episodes each having various stages and lasting for approximately 90-120 minutes. Curious why is it so hard to break the sleep cycle in between??
There are two types of human sleep- NREM(non-rapid eye moment) and REM(rapid eye moment).
A human sleep episode begins with a short period of NREM which lasted for approximately 1.5-2 hours, followed by another short period of REM sleep which lasted for about 5-10 minutes, and then the sleep episode repeats with alternating cycles between NREM and REM throughout the night. Dreaming is most often associated with REM sleep and it is also important for memory consolidation.
Deep sleep occurs in the final stage of NREM sleep and once you started a sleep episode, it will be hard to break the cycle in between. Thus, your brain manipulating you to sleep almost two hours instead of the 5-10 minutes that you planned.
#Source_of_Study:
- Altevogt, Bruce M., and Harvey R. Colten, eds. “Sleep disorders and sleep deprivation: an unmet public health problem.” (2006).