Sleep is regulated by the circadian rhythm, or the sleep wake cycle. It is the 24 hour clock in our brain that determines alertness or sleepiness based on the light changes in our environment. This response in humans has been shaped by humanity's need to adapt to changes in our environment and evolved to give humans their best chance to avoid extreme temperatures, dangerous radiation, and find food most reliably.

Although light and dark are the biggest influences on circadian rhythms, other influences include food intake, stress, physical activity, social environment, and temperature. In our modern era, new influences include nighttime light pollution and shift work, and these can have detrimental health impacts.

When your body's clock determines its almost time to sleep your pineal gland begins to produce melatonin. Melatonin can also be ingested as a sleep-aid on a short term basis. If you're interested in taking melatonin for sleep, its important to keep lights low before bed and limit technology that could confuse your brain about the sleep/wake cycle. Importantly, if you are pregnant, breastfeeding, or have autoimmune or seizure disorders or depression, melatonin could be dangerous.

If insomnia or all-nighters are impacting your functioning, you might be falling victim to "microsleeps," or naps that only last seconds. Alarmingly, even those getting 6 hours of sleep nightly for 14 days have as many microsleeps as those pulling an all-nighter- they are just less cognizant of their fatigue.

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