Category: sleep

>Sleep and teenagers


Sleep (or lack of…) is an interesting topic. Quality of sleep has been shown to negatively affect human performance for various reasons. Furthermore, there have been numerous reports suggesting a link between lack of sleep and depression.

The relationship between short sleep duration and depression has been suggested to be bidirectional,1 with chronic partial sleep deprivation being a potential risk factor for depression. Cross-sectional studies have found relationships between inadequate sleep and depression in adolescents,2,3 and a longitudinal study has shown that getting less sleep over time increased the symptoms of depression among middle school students.4 Short sleep duration has also been shown to be associated with suicidal ideation5 and suicidal behavior6 in adolescents and adults7 in cross-sectional studies.

A recent quasi-experimental study conducted by Gangwish et al. (2010) has looked at the relationships between parental set bedtimes, sleep duration, and depression in adolescents to explore the potentially bidirectional relationship between short sleep duration and depression.

For this scope they analysed 15,659 US adolescents in grades 7 to 12. The results showed that adolescents with parental set bedtimes of midnight or later were 24% more likely to suffer from depression (OR = 1.24, 95% CI 1.04-1.49) and 20% more likely to have suicidal ideation (1.20, 1.01-1.41) than adolescents with parental set bedtimes of 10:00 PM or earlier, after controlling for covariates. Consistent with sleep duration and perception of getting enough sleep acting as mediators, the inclusion of these variables in the multivariate models appreciably attenuated the associations for depression (1.07, 0.88-1.30) and suicidal ideation (1.09, 0.92-1.29).

From Table 3
Odds ratios (95% CI) for depression

Model 1a Model 2b Model 3c Model 4d
Parental set bedtime on weekday nights
10:00 PM or earlier 1.00 1.00 1.00 1.00
By 11:00 PM 1.15 (0.94-1.40) 1.13 (0.90-1.42) 1.10 (0.87-1.39) 0.97 (0.76-1.24)
By or after midnight 1.42 (1.21-1.67) 1.28 (1.07-1.52) 1.24 (1.04-1.49) 1.07 (0.88-1.30)
Self-perception of how much parents care
1 – Not at all 6.82 (3.11-14.98) 5.88 (2.79-12.40)
2 – Very little 8.32 (4.58-15.12) 6.73 (3.49-12.98)
3 – Somewhat 5.50 (3.72-8.13) 4.93 (3.32-7.30)
4 – Quite a bit 2.43 (1.89-3.13) 2.16 (1.69-2.76)
5 – Very much 1.00 1.00
Adolescent-reported sleep duration
≤ 5 h 1.71 (1.22-2.39)
6 h 1.29 (0.97-1.70)
7 h 1.19 (0.96-1.48)
8 h 1.00
9 h 1.17 (0.88-1.56)
≥ 10 h 1.34 (0.95-1.89)
Enough Sleep 0.35 (0.28-0.43)
aModel 1 – Unadjusted.
bModel 2 – Adjusted for age, sex, race/ethnicity, parent’s marital status, and family receipt of public assistance.
cModel 3 – Adjusted for variables in Model 2 plus self perception of how much parents care.
dModel 4 – Adjusted for variables in Model 3 plus adolescent reported sleep duration and perception of getting enough sleep.

The results from this study provide new evidence to support the notion that short sleep duration could play a role in the etiology of depression. Earlier bedtimes could therefore be protective against adolescent depression and suicidal ideation by lengthening sleep duration.

Young athletes have to cope nowadays with various stresses, not only performance related. Studying, maintaining social contacts, training, family and peer pressure are all parts of young athlete’s  lives. Sleep is a simple thing that can make sure they recover properly and can cope with everything they have to deal with.

So, are we making sure they get good quality and good amounts of sleep?

Do we advice them on appropriate bed time?

Do we make sure they don’t spend the night playing videogames or chatting on social networks?

Do we create the right sleeping environment and routines?

Do we know if they are sleeping well?

How about a checklist?

Read Atul Gawande’s book about checklists, The Checklist Manifesto. Not only is the book loaded with fascinating stories, but it honestly changed the way I think about the world. The book’s main point is simple: no matter how expert you may be, well-designed check lists can improve outcomes. So, let’s make sure our young athletes tick all the boxes when it comes to sleep.

>Sleep is good for you


Sunday is one of my favourite days as I tend to have time to do some reading. I like to read everything, but today i particularly enjoyed something recently published on sleep using an interesting animal model.

The benefits of sleep seem obvious. However, scientists have long debated precisely how it improves brain performance at the cellular level. One theory argues that sleep reduces the unimportant connections between neurons, preventing brain overload. Another theory maintains that sleep consolidates memories from the previous day.

I have previously discussed in this blog the importance of sleep for athletes with particular reference to the possibility of videogames altering the normal sleep-wake cycle.

Recent work published on Neuron shows how the circadian clock and sleep affect the scope of neuron-to-neuron connections in a particular region of the brain. The authors also identified a gene that appears to regulate the number of these connections.

The study was conduced studying the larvae of a common see-through aquarium pet, the zebrafish. Like humans, zebrafish are active during the day and sleep at night.

The researchers, led by Lior Appelbaum and Philippe Mourrain of Stanford University, tagged the larvae neurons with a dye (Synaptophysin,  pre-synaptic marker) so that active neuron connections, or synapses, appeared green, whereas inactive ones appeared black.

High-quality image (930K) - Opens new window

After following the fluctuations of these synapses over the course of a day, the team found that the zebrafish did indeed have lower overall synapse activity during sleep.

The scientist are pretty much of the impression that sleep is an active process that reduces the activity in the brain. This reduction in brain activity allows the brain to recover from past experiences.

Without the synapse reduction that happens during sleep the brain would not have the ability to continually take in and store new information. So the importance of sleep i an athletic population is not relevant only for physical recovery, but possibly to facilitate learning and memory all activities incredibly important in sports where tactical aspects are crucial.

More studies are needed but this particular study provides the first insights on NPTX2, a protein implicated in AMPA receptor clustering which modulates circadian synaptic changes. Overexpression of NPTX2b in hypocretin/orexin (HCRT) neurons induces melatonin resistance, so for sure there is a need for more studies in this field to understand the links between sleep and brain function.