Tuesday, 26 July 2011

Around the Clock Doc

On the bus this week there was a poster advertising "around the clock" access to an NHS GP to the residents of Lambeth & Southwark. We are lucky in the UK that we can have access to health services at any time of day or night, which is great for when emergencies arise.

Free access to emergency healthcare information: NHS bus advert to patients in Lambeth & Southwark
However, are GPs making full use of the "time-of-day" information in their diagnosis of disorders?

Last Summer I went on a fascinating Chronobiology course in Germany where we studied how the time of day can affect biology.

One of the parts of the course involved wearing a portable blood pressure monitor that monitored my blood pressure every hour over the course of a day and night. It was a bit annoying having this contraption on my arm, but I did manage to stay focused in the lectures and get some sleep at night time whilst wearing it.

The results were really interesting. There was a clear daily rhythm in my blood pressure, dipping low at night and rising again during the day.

I was also classified as a "white-coat hypertensive", i.e. I had high blood pressure at the start and finish of the recording, when I knew someone was monitoring it. So I know in future to be careful not to be mis-diagnosed as hypertensive at the doctors.

It is normal for your blood pressure to dip at night, whether or not you are sleeping at the time. But some cardiovascular problems cause your blood pressure to remain high at night, in this case, it's better to take your blood pressure medication before going to bed. However, if your blood pressure does still drop at night normally, then it's better to take this medication in the morning, when the blood pressure will be rising.

Your circadian profile of blood pressure can help a doctor diagnose any problems, and indicate which treatment is best for you
There was one case our lecturers were relating to us about a person who was feeling really ill. When they monitored his circadian blood pressure profile they could see his blood pressure dipped dangerously low at night, and the medication he was taking just before bed was making it dip even lower.

Portable blood pressure monitors are expensive but the results can really help with diagnosis of cardiovascular problems. Blood pressure is a clear example of how our body changes over the course of 24 hours, and how by monitoring and understanding this condition we can improve our health services.

Sunday, 17 July 2011

Jet lag

July is with us, and with it the Summer holidays, the season for travelling abroad. For some of us, that’ll mean travelling across many time zones that confuses our body clock and causes “jet lag”.

Our ancestors didn’t have to worry about “horse-and-cart-lag” or “boat-lag”, but due to the advent of high speed flight we can put our body in a different time zone very quickly.

Our ancestors didn't have to worry about the effects of crossing time zones quickly on their body clock. Image (C) Jungle_Boy

When we suffer jet lag, the rhythms of our different organs become out of sync with one another. Our stomach wants food at the wrong time; we are wide awake at night and sleepy during the day; our hearts have low blood pressure during the day when we are being active.

To top this off we can suffer symptoms from flying itself: dry mouth from the air conditioning, cramped muscles from sitting still for so long, tiredness from not sleeping well.

To maximise the fun we have on holidays I have provided some tips to minimise the effects of flying and to resynch to the new time zone as quickly as possible.

To prevent the short term effects of flying, and this includes when flying northerly or southerly where you won’t change time zones, follow these tips:

1. Drink plenty of water, and less caffeine, carbonated drinks, and alcohol.
2. Walk around on the plane and do regular leg exercises. Loosen or take off your shoes.
3. Plan your trip to arrive in the evening, this way you can sleep off the travel fatigue when you arrive.

Strategies to adjust your body clock rapidly to the new time zone depend on whether you are flying East or West. When going East you need to wake up earlier, this effectively shortens the day. When going West you need to stay up later, effectively lengthening the day. Most people’s body clock runs slightly longer than 24 hours, so it’s easier to stay up later, and therefore westward travel can be quicker to adapt to.

If anyone can think of a better pneumonic for westward travel being easier - let me know! (C)  Helen Moore, 2010

In the days before you travel:

Eastwards travel (2 timezones or more):
1. Go to bed earlier, and wake up earlier. Try and get plenty of sleep and rest.
2. Eat your meals earlier. Have a good meal before your flight.
3. Exercise in the morning.

Westwards travel (3 timezones or more):
1. Stay up later, and lie-in in the morning. Try and get plenty of sleep and rest.
2. Eat your meals later. Have a good meal before your flight.
3. Exercise in the afternoon.

When you arrive at your destination:
1. Work your schedule according to the local time zone.
2. Set your alarm clock.
3. Exercise in the morning, preferably outside (even a 30-min walk will help).
4. Expose yourself to bright lights in the morning, and dim lights in the evening (wearing dark sunglasses in the evening can help).
5. Have some fruit or sugary snack by your bedside to suppress night-time hunger – no caffeinated food (including chocolate).
6. Don’t have caffeine within 5 hours before bedtime.
7. Take a 20 minute powernap in the afternoon if you are struggling to stay awake.