Most people notice that they naturally experience different levels of sleepiness and alertness throughout the day. But what causes these patterns? Sleep is regulated by two body systems: sleep/wake homeostasis and the circadian biological clock.
When we have been awake for a long period of time, sleep/wake homeostasis tells us that a need for sleep is accumulating and that it is time to sleep. It also helps us maintain enough sleep throughout the night to make up for the hours of being awake.
Sometimes getting a better nights sleep can be as simple as changing bad habits that might be hindering your ability to get the quality sleep you need. Review these tips to learn how take steps toward a good nights rest.
The sleepiness we experience during these circadian dips will be less intense if we have had sufficient sleep, and more intense when we are sleep deprived as determined by the sleep/wake homeostasis. The circadian rhythm also causes us to feel more alert at certain points of the day, even if we have been awake for hours and our sleep/wake homeostasis would otherwise make us feel more sleepy. The combination of sleep/wake homeostasis and the circadian clock forms the basis of what is known in sleep medicine as the two-process model. This is what explains the need for sleep in our daily lives.
How is our circadian clock set?
The timing of our internal circadian clock takes cues
for synchronization to our daily schedule by "time
givers." By far, the strongest of these is light. Light
in the morning prevents the circadian clock from
becoming delayed while light in the evening may delay
the circadian clock. The opposite is also true with
regards to advancing the circadian clock. Less important
time givers include meals, social interactions, and
Can the circadian clock be set wrong?
Circadian disruptions such as jet lag and shift work
put us in conflict with our natural sleep patterns.
These disruptions of time and light force the body to
alter its normal pattern to adjust. This is why jet lag
can leave travelers feeling poorly and having more
difficulty thinking and performing well. These symptoms
can also occur in everyday life, when the circadian
rhythm is disrupted by keeping long and irregular hours.
Because of this, it is important to keep a regular sleep
schedule and allow plenty of time for quality sleep,
allowing these two vital biological components -- the
sleep/wake restorative process and the circadian rhythm
-- to help us perform at our best.
How can the circadian clock be reset?
For those individuals whose circadian clock becomes misaligned with their daily activities there are a couple of interventions that can be used to bring it back to an optimal cycle.
Though light and melatonin are widely available, we encourage you not to set out on intentionally adjusting your circadian clock without first consulting a sleep specialist. There are aspects of response to these stimuli and side effects from them that must be considered on an individual basis prior to implementation.
See our list of tips for successful sleep...