Relationships start to lose their sexual ‘spark’ after just one year, according to a new study.Researchers found that in the first 12 month ‘honeymoon’ period 15 per cent of couples have sex every day, compared to just one in 20 - five per cent - of other couples. More than half of couples that have been together for up to four years - 53 per cent - have sex a few times a week.But after four years that number dwindles to just a few times a month for 43 per cent. For couples that make it past 15 years together, 15 per cent only have sex a few times a year. Overall, Britain’s bedroom antics leave a lot to be desired with 40 per cent describing their sex life as just ‘okay’ or admitting it ‘could be better’.While a further three-quarters - 76 per cent - admit that they could perhaps try harder between the sheets.When asked what they would do to spice things up in the sack, 33 per cent said lubrication while 24 per cent believed dressing up or watching porn would help.For a disappointing 17 per cent ‘turning off the light’ was the extent of their efforts.Nearly a third - 30 per cent - admitted that at some point they have had problems getting aroused in the first place, according to the research by Lloydspharmacy Online Doctor who questioned 2,000 people in relationships.Dr Tom Brett, medical director at Lloydspharmacy Online Doctor, said: ‘It seems Brits have a lot to learn when it comes to enhancing their sex lives but sometimes not being ‘in the mood’ isn’t just about being tired, stressed or even fancying your partner but a symptom of a medical condition. ‘Erectile dysfunction will affect one in 10 men in the UK each year. However, our research has shown that very few are willing to take control.’While more than half of women said they would be happy for their partner to take an erectile dysfunction (ED) medication to enhance their sex life less than a fifth of men (18 per cent) would consider taking it.Although ED medicine is only available on prescription, one in eight said if they needed it they would get it from a friend or family member, a fifth thought they could buy it off the shelf in the supermarket and one in 20 would click onto an email offering a well-known ED medicine.Dr Brett added: ‘Before taking an ED medicine you must visit a medical professional, either face to face with your GP or, if you find that too embarrassing, through a regulated website such as Online Doctor for a full medical assessment. ‘The underlying causes of that missing spark could be symptomatic of a very treatable condition so getting checked out could be worth more than just improving your performance.’