How is a weekend lie-in bad for you? Experts at Czech Academy of Sciences investigate sleep and our biological clock
How can food improve our internal sleep cycle? Whether the bad effects of an irregular sleep schedule can be mitigated by diet and exercise is currently under investigation by a team at the Czech Academy of Sciences.
After five days of commuting and working, it’s all too tempting to sleep in at the weekend. We feel like we’ve earned it, and the later start may actually be more in tune with humans’ ‘chronotype’ as a species. However, these days off the more unusual sleep schedule can do some psychological harm, upsetting our inbuilt circadian rhythms – the internal body clock that regulates how alert we are throughout the day.
The mismatch between work duties and the natural settings of the body is bound to make us feel bad. Tereza Dočkal, a PhD candidate at the Institute of Physiology of the Academy of Sciences, elaborates:
“We have a completely different regime during the week, because we go to work or school, and this regime is set by our social convention. We can't do anything about it, but when the weekend comes, we tend to sleep in and return to our natural chronotype. This is worst for night owls, who tend to go to bed really late at night and wake up around lunchtime. This is how our rhythms get hugely desynchronised, because the weekend ends and we're forced to wake up a few hours earlier on Monday.”
This is a big problem for people who work shifts; even after a long night, they can't get much sleep.
“Even if I go to bed at four, my clock will automatically say, 'No, we'll get up at nine, for example,' and I'm definitely not able to sleep through the jet lag.”
The unpleasant effect of this de-synchronisation, the ‘social jet lag’ at the start of the working week, is the object of study for Tereza Dočkal and her team. In particular, their research looks at the question of what we can do to remedy the problem, when, for many people, changing sleep patterns is not an option.
When every cell of the body has its own clock, it is important that they are all active at the same time. Most are activated by light, but diet or exercise can also play a role. The team’s published findings so far have demonstrated that the biological clock in the choroid plexus (tissue in the brain ventricles, involved in the production of cerebrospinal fluid) is affected not only by light, but also by the times when we eat.
The benefits of controlled food intake are therefore what the scientists are studying with the help of assistants: mice. Katerina Semenovich at the Institute of Physiology explains the rodents’ role:
“One idea is that we can correct social jetlag, or any kind of jetlag, by synchronising food intake, so that food is served only during a limited part of the day or night. There are even studies where they limit total caloric intake … We are shifting the light regime of the mice by six hours, and we do this every week. We have an open record here where we can see food intake; each dot for each mouse means one pellet, and we measure this in great detail for each animal twenty-four hours a day, every day.”
Can a lack of sleep and a mouse’s biological clock, upset by a variable light regime, be helped by a regular diet? This is the team’s research question, and they expect to have definitive results within two years.
