What Makes a Person Want to Sleep

Everyday we have this drive to want to sleep and there are a couple factors driving it. For starters, a compound known as adenosine, which builds up naturally in the blood as time awake increases. As you sleep each night your body breaks down this compound. This may be what your body uses to keep track of sleep and if you lose sleep the job isn’t completely finished because not all the adenosine has been removed from the blood. An accumulation of adenosine and other factors might explain why, after several nights of bad sleep, you build up a sleep debt that you must make up by sleeping longer than normal. At some point, a lack of sleep will catch up with you.

The time of day when you feel sleepy and go to sleep is also governed by your internal “biological clock” and environmental cues, the most obvious being daylight and darkness. There are a tiny bundle of cells in our brains that act as our biological clock that responds to light signals received through our eyes. As darkness falls, the biological clock triggers the production of melatonin. This hormone makes you feel drowsy as it continues throughout the night. Because of your biological clock, you naturally feel the sleepiest between midnight and 7a.m. You may also feel a second and milder daily “low” in the midafternoon between 1 p.m. and 4p.m. At that time, another rise occurs in melatonin production and might make you feel like sleeping. It is our biological clock that makes us feel alert during the day and drowsy in the early morning hours.

Next – Benefits of Sleep

References: US Department of Health and Human Services