Russell Foster: The health effects of bad sleep

In this episode of Titans of science, body clock guru Russell Foster chats about the discovery of the body clock's mechanisms, as well as what can happen if you upset your body's balance...

Chris - So if we screw around with the body clock, for instance, I do go abroad and cross time zones, or more commonly for most people, you end up pulling a night shift, pulling an all-nighter. Or in radio, working the breakfast show <laugh>, horrible, A&E shifts for me, did it for me. I didn't want to ever do A&E again. What effect does that have? I know I felt pretty awful, but are there health consequences from that?

Russell - There really are and sort of a misfiring, a misaligned biology can produce short-term effects and also long-term effects. So the things that many of us have experienced as a result of sort of short-term disruption, whether that be jet lag or or night shift work even just a couple of days, you find that your emotional responses start to fall apart. So you see greater fluctuations in mood, greater irritability, increased anxiety. Loss of empathy. I think this is fascinating. You fail to pick up the social signals of your friends, colleagues, and the people you live with. Increased frustration, risk taking and impulsivity. This is also fascinating. The tired brain does stupid and impulsive things, 'ooh, I think I can go through that traffic light before it turns red.' This is daft. You'd never think of doing it if your brain wasn't tired. And also the tired brain remembers negative experiences, but forgets the positive ones. So your whole worldview is based upon, you know, negative information. So that's some of the emotional things that can happen. Our cognitive responses. While our entire cognitive performance is impaired to a greater or lesser extent, depending on how much disruption you get. One thing that goes pretty quickly is your ability to multitask. So we are bombarded with bits of information and we have to prioritise what we're going to respond to. And that prioritisation falls apart when we're tired. Memory consolidation, information processing, and coming up with novel solutions to complex problems is profoundly affected by lack of sleep. Concentration, communication, decision making. All of that can be really badly disrupted. Then we go into sort of the longer term impacts. As you see in night shift workers after 5, 10, 15, 20 years. One thing that can happen fairly early on is microsleep; falling asleep at the wheel. And a study incidentally from junior doctors, showed that 57% of junior doctors had either had a crash or a near miss on the drive home after the night shift. Then we have altered stress responses. Perhaps the only way you can deal with being chronically tired and to stay awake is to activate the stress axis. Now the stress axis gets a bad wrap. It's a really great short term. It's like the first gear of an engine for a car. It gives you that acceleration to get away. But if you keep the car in first gear, then you're going to destroy the engine. And so what you see is lowered immunity, some really very interesting stuff there. One night of no sleep before vaccination can actually reduce the efficacy of that vaccination, very significantly so. Tired people show a lowered antibody response to vaccination. You see higher rates of cardiovascular disease. And this lowered immunity has been associated with increased levels of cancer. And in fact, the data are so strong that the World Health Organization has designated night shift workers a probable carcinogen. And of course, poor sleep increases the vulnerability to depression and psychosis. There's even some data suggesting that really poor sleep during the middle years can be a risk factor for dementia later on in life. And the connection seems to be this recently discovered glymphatic system, which you can think of as a clearance system within the brain. And one of the things it does is to get rid of a misfolded protein called beta amyloid. And beta amyloid has been associated with a high risk of dementia and Alzheimer's. So there's some serious impacts driving our biology outside of its normal range.

Chris - The body also does other important things when we sleep, it releases various hormones, growth hormone, for example. So we grow, we repair at night. So what are the impacts then? If we think about medical treatments, if we've got a disturbed body clock or we give certain treatments at certain times of the day, does that mean they're going to be better and work better if we give certain drugs and certain things at certain times of the day?

Russell - This is such an important point Chris, because chronopharmacology, giving a drug when it's most effective, I think is going to be one of the really exciting areas of development in the coming decade or so. But we know that there's an increased risk of a stroke between 6AM and 12 noon. The increased risk is about 50% compared to any other time of the day. So you could say, well, what time should I take my antihypertensive? And, and of course, because people know that the strokes have a high frequency first thing in the morning, the sort of knee jerk reaction is, well, you take it in the morning. But if you think about it, by the time you've actually got up, you've taken the drug and it's actually getting into the body to have an effect, you are past that dangerous window. So a Spanish group looked at taking your antihypertensives either first thing in the morning or immediately before you go to sleep, bedtime. And it had a really big impact on long-term survival. Over a study period of over 10 years, there was a 50% drop in death rate for those individuals who took their antihypertensives before they went to bed compared to those individuals that took their drugs in the morning. Other areas such as cancer have turned out to be really fascinating. Fairly old studies now in childhood leukaemia showing morning versus evening treatment with chemotherapy. The kids that were on the evening chemotherapy had 75% survival versus 35% survival for the kids that had it in the morning. And so there's big differences. Our body doesn't do the same thing. And so it's going to process drugs at different times.