What are Circadian Rhythms?

Circadian rhythm also known as sleep/wake cycle is 24 hour internal clock running in the background of your brain & cycles between sleepiness & alertness at regular intervals. You must have observed that you feel active & sleepy /lazy at the same time every day.

For adults, fall in activeness happens during peak hours of sleep from 2:00 am to 4:00 am & post lunch from 2:00 pm to 3:00 pm. However, this does not necessarily apply to everyone, specifically those who are morning people(who wake up early). When you have proper sleep, you would not observe high swings in your circadian rhythm/sleep & alertness.

A part of your brain (a part of hypothalamus) controls your Circadian rhythm. External factors such as light & darkness also impacts Circadian rhythm. When it is dark, your eyes gives signal to the hypothalamus that it’s time to feel tired. Your brain in turn gives signal to your body to release melatonin which makes you feel tired. This is the reason why your circadian cycle tend to talk to cycle of daytime & nighttime( that’s why shift workers.

Your circadian cycle bests works when you have regular sleeping habits such as going to bed at night, getting up early in the morning around the same time every day ( including weekends). However in outlier events such as jetlag, daylight saving or watching sports late night, your circadian cycle is impacted. Such disruptions in circadian rhythm can result in chronic diseases such as cancer, diabetes, heart disease, depression & obesity. In most of the cases, such disruption also leads to constipation & deteriorates gut health.

Working in shifts, jet lag and spending more time in front of the television, computer or smartphone can lead to circadian rhythm disorder. Poor quality sleep leads to conditions such as sleep apnea, stress, work pressure or not getting enough rest can make the problem worse.

What we eat & when we eat also impacts our circadian rhythm. Keep a regular routine of eating & sleeping( including weekends) makes your circadian clock running smoothly. Target to have at least 7 to 8 hours of sleep everyday & stay away blue light during evening hours. This essentially means staying away from laptop & mobile during evening.

Given that during darkness, your body feels tired (as discussed in above paragraphs), your dinner should be really light since you do not need to have much activity that warrants higher food consumption. Keeping less than 2 hours ofgap in your eating & sleeping further adds to your weight gain/obesity. It is recommended that:

1. Your breakfast should be heavy followed by light to medium lunch & light snacks.
2. You should not have your dinner after sunset given your circadian clock coincides with sleep during evening hours.

Circadian rhythm also varies depending upon your life stage. It is also impacted by your lifestyle & health. For instance Teenager, who go to bed and wake up later as compared to adults feel more alert in the evening because their melatonin levels don’t increase until later in the day, so they don’t really feel tired before 11:00 p.m. Their energy typically drops off between 2:00 and 5:00 p.m. and 3:00 and 7:00 a.m.

The following sleep hours are recommended based on the category you fall into:

• Newborns (0-3 months): Sleep range narrowed to 14-17 hours each day
• Infants (4-11 months): Sleep range widened two hours to 12-15 hours 
• Toddlers (1-2 years): Sleep range widened by one hour to 11-14 hours
• Preschoolers (3-5): Sleep range widened by one hour to 10-13 hours 
• School age children (6-13): Sleep range widened by one hour to 9-11 hours 
• Teenagers (14-17): Sleep range widened by one hour to 8-10 hours 
• Younger adults (18-25): Sleep range is 7-9 hours 
• Adults (26-64): Sleep range is 7-9 hours
• Older adults (65+): Sleep range is 7-8 hours 

Women who sleep less than six hours a night may have more belly fat , while men are likely to have both bigger waists and metabolic syndrome if they sleep less than six hours. On the other hand, women who sleep 10 or more hours have a much higher risk for metabolic syndrome, while in men it correlates to higher triglyceride levels as well.