Weather keeps changing and I get ill easily. What can I do?

Getting ill more often when the weather changes has more to do with sleep and daily routines that shift with the weather than with the weather itself, and no vitamin can be said to keep you from getting ill. What you can do is keep the basics steady: sleep 7 hours or more, wash your hands with soap for at least 20 seconds, and stay active.

Why do I seem to get ill more easily when the weather keeps changing?

When the weather alternates between heat and rain or changes quickly, it is not only the temperature that shifts. Daily life shifts with it.

Sleep changes

Hot, sticky nights or heavy rain lead many people to go to bed late, sleep in broken stretches, or wake at irregular times. Small losses of sleep can add up to ongoing short sleep without you noticing.

Meals change

On rainy or very hot days, people tend to go out for food less, eat at irregular times, or eat fewer vegetables and fruit than usual.

More time indoors with other people

When going out is harder, we spend longer in air-conditioned rooms, on public transport or in shopping centres, and move less. The UK's NHS states that the germs behind common respiratory illnesses spread through coughs and sneezes and can live on hands and surfaces for up to 24 hours, so spending time close together in enclosed spaces raises the chance of picking them up.

The weather keeps changing and I get ill easily. Which vitamins should I take?

No vitamin can be said to keep you from getting ill. The NHS says there is little evidence that vitamin or herbal supplements stop you getting ill or help you get better more quickly. What relates to getting ill easily when the weather changes is daily routine, not the choice of one particular vitamin.

What you can do day to day

• Sleep 7 hours or more regularly, as the CDC recommends.
• Wash your hands with soap for at least 20 seconds, especially after coming home and before eating.
• Get at least 150 minutes of moderate activity a week, as the WHO recommends.
• When you are ill, stay home and do not share towels or cups with others.

Each of these is covered in the sections below.

Everyday eating: a general guide, separate from illness

Food is not a way to prevent illness, but it is part of overall health. As a general guide for everyday eating, the World Health Organization (WHO) says everyone older than 10 should eat at least 400 g of fruit and vegetables a day, limit free sugars to less than 10% of daily energy intake, and that adults should eat less than 5 g of salt a day (2 g of sodium).

Does short sleep make you more likely to get ill?

Research suggests a link. Prather and colleagues (2015) measured the sleep of 164 healthy adults aged 18 to 55 with a wrist device for 7 days, then gave them a virus through nasal drops and monitored them for 5 days. Those sleeping less than 6 hours a night were more likely to get ill than those sleeping more than 7 hours, but this was a small study and the results carry a lot of uncertainty. Those sleeping 6 to 7 hours were not clearly different.

How much sleep is enough?

The US CDC recommends 7 or more hours for adults aged 18 to 60, 7 to 9 hours for ages 61 to 64, and 7 to 8 hours for those 65 and older.

On hot or rainy nights

• Go to bed and wake at close to the same times every day, including days off.
• Keep the bedroom quiet and cool.
• Turn off electronic devices at least 30 minutes before bed.
• Avoid large meals and alcohol before bed, and caffeine in the afternoon or evening.

How should I wash my hands to reduce the spread of germs?

The CDC lists regular handwashing and cleaning commonly touched surfaces among the basic steps for reducing the spread of respiratory germs.

Steps for handwashing

1. Wet your hands with clean, running water (warm or cold) and apply soap.
2. Lather the backs of your hands, between your fingers and under your nails.
3. Scrub for at least 20 seconds, about as long as humming "Happy Birthday" twice.
4. Rinse well under clean, running water.
5. Dry with a clean towel or an air dryer.

When soap and water are not available

Use an alcohol-based hand sanitiser with at least 60% alcohol. The NHS also advises not sharing towels or cups with someone who is ill and not touching your eyes or nose.

It's raining and I can't go out. How can I stay active?

The WHO notes that adults should get at least 150 minutes of moderate-intensity physical activity a week, that all age groups should limit time spent sitting, and that muscle strengthening benefits everyone.

• 150 minutes is about 30 minutes a day on 5 days a week, and it can be split into short bouts.
• On rainy days, take the stairs, walk in a shopping centre, or do bodyweight exercises at home.
• Get up and walk now and then if you sit in an air-conditioned office all day.
• Dress for the temperature, and carry a light layer if you move in and out of air-conditioned rooms often.
• Drink enough fluid, especially on hot days or when you sweat a lot.

When should I see a doctor?

When you are ill, the CDC advises staying home and away from others. The NHS says most people feel better within about 1 to 2 weeks, and advises seeing a doctor if:

• you have a high temperature for more than 3 days, or a very high temperature or shivering
• your symptoms get worse, or do not get better after 10 days
• you have a cough for more than 3 weeks
• you feel short of breath or have chest pain
• you have a long-term medical condition or a weakened immune system
• you are worried about a child's symptoms