14 Day Lag Period Between Sleep Deficit And New Injury

Picture by Jeffrey Bown from his book Goodnight Darth Vader

Well, it's that time of the year again, where school has ended (for Singapore schools) and work in the office starts to wind down. Many of our patients are already traveling before the Christmas holiday.

Many of us, in this last month of the year, will experience less sleep due to travel, parties, family, children and shift work.

Though we would love to catch up with sleep when sleep is disturbed, even with training/ exercising taking a lower priority, it becomes more difficult with all the committments.

I often tell my patients (who are still training seriously) that there is up to 51 percent increased risk of injury especially for endurance athletes who get less than 7 hours of sleep per day in the last 2 weeks (Johnson et al, 2020).

The study recruited runners, triathletes, swimmers, cyclists and rowers. Subjective health complaints (SHCs) like psychological/ lifestyle factors, cardiorespiratory and gastrointestinal problems to investigated to see if they were associated with sleep quality, training load and new injury episodes.

Applying a 7 day and 14 day lag period, a shared frailty model was used to investigate new injury risk associations with total SHCs and sleep quality.

The investigators found that 7 day lag psychological/ lifestyle SHCs were significantly associated with new injury risk. This was in contrast to cardiorespiratory and gastrointesinal SHCs were not significantly associated with new injury risk. 

New injury risk had a significant increased association with a 14 day lag if there was less than 7 hours of sleep per day. There was no significant association with total SHCs, sleep quantity and training load factors.

The authors concluded that athletes need to be aware of the lag period between low sleep quality and its subsequent impact on new injury risk. In order to minimise the risk of new injuries, psychological/ lifestyle SHCs and sleep quantity should be considered.

Be mindful. Bear in mind that this end year period may be a time when we are most susceptible to new injury if we are deprived of sleep.

Reference

Johnston R, Cahalan R, Bonnett L et al (2020). General Health Complaints And Sleep Associated With New Injury Within An Endurance Sporting Population. J Sci Med Sport. 23(3): 252-257. DOI: 10.1016/j.jsams.2019.10.013

How To Wake Up Alert And Refreshed

Do you go to bed early, sleep through the night and still wake up tired and groggy? - Well, it happens to me quite regularly. Turns out that I'm not alone. A study found that fewer than 1 in 3 Americans are getting enough restorative sleep (Robbins et al, 2022). 

You may say that the Americans have more distractions, but in Singapore, 41 percent of adults get between 4 to 6 hours of sleep a night only, even though they should be clocking in 7 to 8 hours.

Not only do we have insufficient sleep, the vast majority of us are not getting the right kind of sleep. So we wake up less alert, have less energy and poor moods in the morning. Low quality and/ or quantity of sleep has terrible far reaching effects, from short term ability to focus to long term risk for chronic diseases.

The good news is that there is a way to fix this. Another published study by Vallat et al (2022) listed 3 steps we can do to eliminate that groggy feeling we get when we wake up. The researchers studied 833 twins and genetically unrelated adults and demonstrated that how effectively one wakes up during the hours following sleep is not assocated with genetics. 

They found 4 independent key factors. sleep quality/ quantity the night before, physical activity the day prior, a breakfast rich in carbohydrates and a low blood sugar level following that breakfast. 

The researchers found that sleeping in for an extra 30 minutes on a morning when you need it was associated with increased alertness in that morning. Physical activity (or exercise) the day before also had a strong link to feeling alert and awake the next morning. The more exercise the better it seems.

Breakfast matters. Participants who ate a breakfast high in low glycemic carbohydrates like whole wheat bread, oats, brown rice felt more alert. However, eating breakfasts that were sugary or high glycemic carbohydrates (muffin, cereal bar, white bread, potatoes) and excessive protein had the opposite effect. 

That's the secret to waking up alert and refreshed every morning. So definitely don't skip breakfast.

References

Robbins R, Quan SF, Buysse DJ et al (2022). A Nationally Representative Survey Assessing Restorative Sleep In US Adults. Frontiers In Sleep. Vol 1. DOI: 10.3389/frsle.2022.935228

Vallat R, Berry SE, Tsereteli SE et al (2022). How People Wake Up Is Associated With previous Night's Sleep Together With Physical Activity And Food Intake. Nat Commun 13,7116. DOI: 10.1038/s41467-022-34503-2