You go back to your cubicle after lunch and find you are getting sleepy, sleepy….No, you’re not being hypnotized by your computer screen; there’s a basic biological mechanism at work urging you to nap. Human beings have a naturally biphasic sleep pattern. This means that your body and mind crave sleep twice a day. You have a powerful drive to sleep at night and a somewhat less urgent, but measurable call to sleep in the middle of the day. What can be measured? Decreases in alertness, body temperature, and cortisol levels all signal that it’s time to nap.
If you want to blame your brain, some of the critical cells involved are clustered in the hyphothalamus, in two small clusters of cells forming the suprachiasmatic nuclei (SCN). When SCN cells are destroyed in rats, the rats lose any rhythmic pattern to their sleep habits. Put the cells back and these sleep patterns are restored.
Sleep patterns are determined by our circadian rhythms, our natural cycles of biological activity. Circadian rhythms are influenced by the expression of certain genes referred to as “clock genes.” Clock genes were first identified in fruit flies and similar genes were later found in other animals, including humans. Researchers at the University of Utah found that a defect in a human clock gene is associated with a rare sleep disorder known as “familial advanced sleep phase syndrome” or FASPS. Individuals with this syndrome get sleepy early in the evening (e.g., around 7 p.m.) and wake up early in the morning (around 4:30 am).
It’s not known how clock genes work in brain cells to control sleep urges at any time, much less at midday. But the effects of some external influences are beginning to be understood. For example, those power lunches don’t help, but you can still blame that on biology. High-carb foods that raise blood sugar too rapidly can cause the body to release an amount of insulin that causes blood sugar to drop too much. When the brain senses decreases in glucose, sleepiness can result. Additionally, circadian rhythms can be influenced by light cues, so dim lighting can increase your desire for sleep.
What can you do to minimize the effects of this biological call to sleep?
- Give in if you can – some companies are allowing power naps.
- Go easy on the high-carb lunches.
- Optimize the lighting in your work space.
- Consider doing those tasks that don’t require a high level of concentration during that period of time.
Of course you may just have to tough it out. But it helps to know it isn’t just the job that’s making you sleepy.