Getting enough regular sleep is essential for a healthy immune system, and to enable relaxation. It is during sleep that the body repairs itself and revitalises organs and muscles. However, virtually all of us have trouble sleeping sometimes.

Those of us who have difficulty falling asleep, insomnia, or wake early, are not alone. A regular lack of sleep causes concentration, mood and energy levels to suffer. This reduces effectiveness, so it can actually increase stress levels. One glimmer of hope comes from a recent research study that suggests the health impact of poor sleep may be partly mitigated by adequate physical activity.

Previous work had suggested that low physical activity could exaggerate the concerning link between inadequate sleep and raised mortality. As such, Dr. Emmanuel Stamatakis of the University of Sydney, Australia, and colleagues examined the synergistic effect of physical activity and sleep quality. They used information on 380,055 men and women from the UK Biobank, followed for about 11 years. Physical activity was categorised as high, medium, low or no moderate-to-vigorous activity. Sleep was categorized into healthy, intermediate, and poor using a composite of sleep duration, insomnia, snoring, and daytime sleepiness.

Most (56%) of the participants had healthy sleep, 42% intermediate quality, and 3% poor. Poor sleep was linked to being older, having a higher body mass index, having mental health issues, smoking and shift work, among other factors. Analysis showed that sleep score was linked to all-cause mortality, as well as cardiovascular and ischaemic stroke mortality. In the British Journal of Sports Medicine, the authors explain that compared with participants with high physical activity plus healthy sleep, those with the lowest activity plus poorer sleep scores were at a 57% raised risk of all-cause mortality.

Their risks of cardiovascular disease, any cancer, and lung cancer specifically were also raised, but stroke risk was not. "The detrimental associations of poor sleep with all-cause and cause-specific mortality risks are exacerbated by low physical activity, suggesting likely synergistic effects," they report. "Our study supports the need to target both behaviours in research and clinical practice."

Many people are tempted to catch up on sleep lost during the week by staying in bed later on weekend mornings. But is this a sensible strategy? Research has also been done on the risks and benefits of weekend sleep patterns. The pattern of staying up late and sleeping in on the weekend was examined by a team from the Medical Research Council in Oxford, UK. They looked at the impact of "social jetlag", a term used to describe the sometimes uncomfortable difference in sleep patterns between work days and free days.

An estimated 87% of the population suffers from social jetlag to some extent, or greater tiredness on, for example, Monday mornings. The team used figures from 815 non-shift working participants in the long-term Dunedin Multidisciplinary Health and Development Study.

Participants were all born in New Zealand between 1972 and 1973, and were followed from age 3 to 38, when 95% of the 1007 study members were still alive. Their height, weight, and waist circumference were measured, along with C-reactive protein, a biomarker for inflammation, and glycated haemoglobin in the blood, a marker for diabetes.

Measurements were combined with results of a questionnaire on sleep duration and the individual's preference in sleep timing, known as "chronotype". Social jetlag was the comparison between each person's midpoint of sleep on work days and on free days. Findings showed that those with a greater difference in sleep patterns on free days and work days had a significantly higher risk of obesity and obesity-related disease, including metabolic disorder (the medical term for a combination of diabetes, high blood pressure, and obesity) and inflammation. Just a two-hour difference in sleep patterns at the weekend was linked to risk of an elevated body mass index and risk of inflammation and diabetes.

Lead author, Dr Michael Parsons, explains that while travel jetlag can cause temporary problems with metabolism, social jetlag "can occur chronically throughout an individual's working life so is more likely to induce more serious, chronic consequences for metabolism." He adds, "Social jetlag is an under researched but potentially key contributor to why living against our internal clock has an impact on our health. Our research confirms findings from a previous study that connected people with more severe social jetlag to increases in self-reported body mass index, but this is the first study to suggest this difference in sleeping times can also increase the risk for obesity-related disease."

Full details appear in the International Journal of Obesity. The team are unsure why social jetlag may cause the raised risk, but suggest it may be that it disrupts healthy habits such as diet and exercise in a way that may compromise health. "Further research aimed at understanding that the physiology and social features of social jetlag may inform obesity prevention and have ramifications for policies and practices that contribute to increased social jetlag, such as work schedules and daylight savings time," they add.

For those with concerns over the quality or quality of their sleep, here are several tips to improve the situation and get a good night's rest:

• Stick to a regular bedtime, and try not to sleep in late on non-working days and push 'against' the body clock. Spending some time outside every day also helps regulate the body clock, as well as benefiting the lungs.
• Regular exercise makes falling asleep, and staying asleep easier, in addition to the benefits described above. But be careful not to exercise too close to bedtime or you may have trouble nodding off.
• Don't have drinks with caffeine or use other stimulants after about 6pm. Caffeine is found in coffee, tea, cocoa, cola and chocolate.
• If you smoke, try to cut down - smokers tend to take longer to fall asleep and wake more often.
• Eat a light dinner no later than two hours before going to bed. Any later, and your stomach will be too busy digesting to allow you to sleep well. Good bedtime drinks are warm milk and chamomile tea.
• Do not drink alcohol near bedtime. It may help you fall asleep initially, but will dehydrate you, interrupting your sleep later on in the night and causing you to wake early.
• Do something to relax before going to bed. Have a warm bath, listen to some quiet music, or do a relaxation exercise. Be peaceful for the hour before you go to bed and your body will unwind.
• Don't work, study, or watch scary films just before bed.
• Deal with worries and distractions several hours before going to bed. Write them down, or make a list of things to do, so you won’t think about them all night. Don't use the bedroom for chores like paying bills, or discussing the day's problems.
• Keep the bedroom quiet, dark, and warm. Sleep on a good quality mattress, and wear soft and cozy nightwear.
• Leave the bedroom if you are unable to sleep. After about 15 to 20 minutes, get up and engage in a quiet activity, such as reading. Return to bed when you are sleepy. You may need to repeat this process through the night. Do not watch the clock during the night and try not to panic about not sleeping.
• Herbal remedies that may aid sleep include Valerian, Passiflora and Kava Kava. A few drops of lavender oil in the bath can work well.
• On a hot night, open windows and doors to create a draft. Remove the duvet and blankets, and wear light cotton nightwear. Have a cool shower or bath before going to bed, and keep a glass of cold water nearby.
• On a cold night, keep the bedroom warm but not too hot, and block any drafts. Use a fleecy under-blanket or use several layers of bedding. Have a warm bath and a warm drink just before bed. Finally, hot water bottles and electric blankets can make all the difference.

A word on insomnia. True insomnia, which affects about 1 in 10 people, is difficulty getting to sleep, staying asleep, or having non-refreshing sleep, three or more times a week for at least a month. Difficulty getting to sleep (sleep onset insomnia) is most common in young people, whereas waking in the night (frequent nocturnal awakening) is most common in older people. Early morning waking is also a frequent problem.

With insomnia, sleep is no longer refreshing and the daytimes are overshadowed by irritability, tiredness, or lack of concentration. Insomnia can last for days, months or even years. If the tips above do not seem to be helping, individuals may consider:

Sleeping pills. Benzodiazepines and newer medications such as Zopiclone or Zolpidem may be recommended. Both types of drugs work in a similar way. Ensure they do not interact with any other medications. Use the lowest dose and never mix with alcohol.

A sleep diary. Keeping a sleep diary to record bedtimes, wake times, hours slept, and sleep quality each morning may help when seeking medical advice. If continued during treatment, a sleep diary can be a useful indicator of progress.

Psychological treatments. Approaches such as cognitive behavioral therapy will focus on behavioral change. They may include methods such as sleep restriction, stimulus control, cognitive therapy and relaxation techniques.

References and Resources

1. Huang, B-H. et al. Sleep and physical activity in relation to all-cause, cardiovascular disease and cancer mortality risk. British Journal of Sports Medicine, 30 June 2021 doi: 10.1136/bjsports-2021-104046
   https://bjsm.bmj.com/content/early/2021/05/25/bjsports-2021-104046
2. Parsons, M. et al. Social Jetlag, Obesity and Metabolic Disorder: Investigation in a Cohort Study. The International Journal of Obesity, 20 January 2015 doi: 10.1038/ijo.2014.201. https://www.nature.com/articles/ijo2014201

About the Author:
Jane Collingwood is a medical journalist with 17 years experience reporting on all areas of medical research for online and print publications. Jane has also worked on a range of medical studies funded by the UK National Health Service within the University of Bristol in the South West of England. Jane has an academic background in psychology and has authored books on stress management and respiratory infections. Currently she is combining journalism with a national coordinating role on the UK's largest surgical research trial.