To sleep in or not to sleep in

A study released last week suggests that sleeping in over the weekend may let you live longer. This is contrary to our advice that sleeping in causes circadian clock shifts that compromise metabolism, mood and accident/health event risk.

So, what is the truth?

The study is a large sample of 43,880 people over 13 years which is good.  Measures were self-reported and not validated by specific measures. The conclusions:

1.    Sleeping too little or too much increases mortality (key message)

2.    Those who sleep too little and catch up on weekends reduce mortality

The advice that comes from an important study is that we should sleep in.  However, it fails to mention the well-recognised risks of sleeping in.  This is variously called Delayed Sleep Phase Syndrome, Social Jet Lag or just “blue Mondays”.

The consequences have been linked to more heart attacks, Monday morning accidents, Monday suicides, mood disorders and significant metabolic risk such as weight gain, appetite dysregulation and diabetes. Check in Nature 2018 and Science Daily 2017.

The danger of media statements like this is the oversimplification of a very complex topic. The message could lead to unfortunate outcomes.  First, you may think it is OK to compromise sleep during the week.  Second, you may think it is safe to sleep in. There is plenty research showing that neither is safe.

Here is what we believe is a SAFE recommendation:

1.    Get enough sleep. Every human has a certain sleep need which is usually between 7 and 8 hours. While we can absorb and recover from short term (a night) sleep deprivation, repeated short nights lead to a dangerous accumulation of risk to your physical, emotional, and cognitive health and performance. Meeting our sleep need is primary. Most of us fail.

2.    Keep your body clock in tune with the day-night rhythm. This is best done through a quiet, relaxing and device-free evening and exposing yourself to the blue light of dawn. All primates and humans have done this for millions of years. We are diurnal species that get up early to hunt and gather at dawn.

3.    Focus on quality. The sleep cycle is linked to both the circadian and ultradian rhythms. When we are in synchrony deep sleep, immunity, growth, hormones, confidence and cognition are optimised. You will be more likely to sleep through the night.

4. If you have sleep debt, go to bed early. Sleep debt is common as this study and many others show. If you need sleep catch it up by going to bed early. The quality of sleep (deep or slow wave) is far superior than when you catch up with a weekend sleep in.

When you sleep in or travel, this delicately balanced biological rhythm is disrupted. It takes days to reset. Why would you do it every weekend?