There are two major states of sleep, non-REM and REM. Non-REM sleep has three phases, each characterized by different levels of brain activity, while REM sleep is associated with vivid dreaming and rapid eye movement. A perfect night's sleep involves cycling through these phases multiple times.
Scientists have not found any animal that does not need sleep, as all living beings require some amount of recovery, regenerative functions, and chemical rebalancing. However, some creatures with short lifespans such as flies may not need sleep as they do not live long enough to require recovery time.
The three neuromodulators, dopamine, serotonin, and acetylcholine, have a reciprocal dance that generates a natural architecture of sleep throughout the night. Disrupting their balance can negatively impact the stages of sleep.
Arexin, a wake-promoting chemical, is crucial for maintaining regular sleep patterns, and its deficiency can lead to conditions like narcolepsy. Starvation can also lead to insufficient sleep, with testosterone release peaks just before entering REM sleep and during it, as a brain response to stay awake for longer in the absence of food sources.
The pineal gland is a small, pea-sized gland in the human brain that releases melatonin, which is responsible for making us sleepy and facilitating sleep. While some people may consider supplementing with melatonin, it is important to note that it also suppresses the onset of puberty.
Sniffing is used by clinicians to assess a person's brain activity, but during REM sleep, our ability to wake up in response to odors is diminished due to sleepatonia, a healthy paralysis that prevents acting out dreams.