One-third of Indian adults experience sleep debt. Not sleeping enough can increase your risk of hypertension, diabetes, and cardiovascular disease.

We all live in a busy world where the most important resource at our disposal is time itself. There never seems enough time to accomplish everything that needs to be done. There is the 8-hour work day, the need for some family time, chore time (which always seems to take up too much time!), exercise time and then the challenge of carving out some me-time. For some, there is the additional 60 minute to-and-fro commute to work. With so many demands, it would seem obvious that something has got to give. Sadly, the most common thing to give in the working population is the time spent sleeping. As a result people are likely to accumulate what has now been commonly referred to as "sleep debt".

Sleep debt can be determined through a simple calculation. The difference between the sleep you require (say 7 hours) and the sleep that you get (e.g. 5 hours) is what constitutes your sleep debt for the night. In this case, a 2-hour sleep debt has accrued. Unfortunately, one third of Indian adults are thought to be experiencing sleep debt, too large a number given the significant side effects of not sleeping enough.

So how much should we be sleeping?

As per the guidelines developed by the American Association of Sleep Medicine and Sleep Research Society, adults should be sleeping for around 7 hours per night, with children requiring more hours of sleep for the brain to rest and recover. Specifically, children aged 6-12 years of age are recommended to sleep for 9-12 hours, with recommended levels for teenagers dropping slightly to 8 10 hours per night.

A quick reflection on our own habits and those of our loved ones is likely to reveal that perhaps everyone you know is incurring a sleep debt. They all seem to be functioning perfectly well though. So, is sleep debt actually that bad or it just one additional benign lifestyle change to attribute to today's fast paced, competitive world we live in?

Is sleep debt that bad?

Our bodies are remarkable machines. Brief periods of sleep debt while definitely unpleasant in that one feels fatigued and tired, is unlikely to have a long-lasting effect on one's health. Ongoing sleep debt however is associated with a string of ill effects. Unfortunately, being the adaptive machines that we are, our bodies quickly adjust to reduced hours of sleeping, and we come to accept that as our normal functioning. Unknown to us though, we are likely accepting 'sub-normal' activity as normal.

Lack of sleep increases the risk of hypertension and diabetes and is also associated with greater calorific intake and increased belly fat, all risk factors of cardiovascular disease. Sleep debt has negative effects on one's metabolism and can also cause weight gain and increase insulin sensitivity (Depner et al., 2019). From a cognitive perspective, it is now well established that sleep is important for both consolidating memories as well as learning new information (Yoo et al., 2007). The lack of sleep or sleep debt that one typically experiences has also been associated with social withdrawal and loneliness (Simon & Walker, 2018).

Repaying sleep debt

If sleep debt or sleeping less than the requisite amount is so harmful, then the easiest solution seems to be catching up on sleep over the weekend, often referred to as 'catch-up' sleep. Sleeping 10 hours on the weekend to make up for the 5 hours of sleep you lost in the week comes with its own set of problems. For starters, if you wake up late, say at 11 am instead of your regular 6 am, chances are you will struggle to fall asleep at your regular bed time as well. Eventually, you are trapped in a vicious cycle you sleep later than usual and hence when you wake up at your regular time, you have once again accrued sleep debt.

More importantly though, research suggests that sleep debt cannot be paid off so easily. Specifically, we are thought to require around four days to recover from one hour worth of sleep debt (Kitamura et al., 2016). Research with Korean adolescents indicated that increased catch-up sleep on the weekend was associated with poorer performance on attentional tasks even on controlling for weekday sleep duration (Kim et al., 2011). Weekend catch-up sleep then does not reverse the negative impact of sleep on one's cognition.

Perhaps afternoon naps are a better way of repaying sleep debt then. There is some evidence suggesting that a short 30-minute afternoon nap can reduce the impact of night-time sleep deprivation with regard to select mental and physical outcomes (Waterhouse et al., 2007). It is certainly not a blanket remedy though with grip strength and reaction time of afternoon nappers being comparable to individuals that had only slept for 3 hours in the night. Biologically, this should not come as a surprise as short naps do not allow the body to move through all the requisite stages of sleep vital for it to exercise its rejuvenating effect.

The most effective way to make up for sleep debt then, would be to go to bed earlier. Additionally, the earlier the debt is paid off (in whatever way possible), the less likely it is to have a negative outcome on the individual's overall functioning. As with all things though, prevention is better than cure. Putting systems in place to allow one to have a good night's sleep and not accrue a sleep debt at all would be the best way forward.

Cultivating good sleep habits

The good news is that sleep is a behaviour quite amenable to change through the use of environmental modifications. For starters, ensure that your bedroom is dark and calming. Avoid doing work in the bedroom so that the bed remains associated only with relaxing activities. Try to spend the 30-60 minutes before bedtime in the company of non-screen activities. Some people may find that having a warm shower or consuming a glass of warm milk before bedtime helps them fall asleep. Lastly, if you struggle to fall asleep after about 20 minutes of trying, engage in some other calming, non-screen-based activity. Most importantly, schedule in around 7 hours of sleep per night because a good night's sleep is nothing short of an investment in your wellbeing.

This article has been authored by Prof. Deepa Bapat, Adjunct Faculty of Psychology, FLAME University.