Can I use lavender to help with aches and pains/a stiff neck? And how should I use it to aid sleep?

Lavender is one of the most popular aromatherapy products. It has many beneficial uses, and can help with the healing of headaches, tension, stress, pain and infection. Dried lavender can be used to make a herbal tea, in which a cotton towel can in soaked for use as a compress. This towel can then be applied to the area experiencing muscular tension.

You can but for muscular tension there are more oils that will help more , you would use lavender for relaxing, and may be some thing like black pepper for muscular tension hope this helps

All of the other answers are great, one suggestion I would make as far using the dried flowers are concerned is that you could use them in the bath! you could tie about a tablespoon ful in a piece of net, hang it on the bath tap and let the hot water flow through it as you are running the bath, or you can just put a handful into the bath. you will still get the wonderful relaxing aroma and the heat from the bath will help both you and your muscles to relax. Please be advised though, using too much of any essential oil can cause problems. If the same oil is used too often, you can become sensitised to it! Lavender oil is good for treating dermatitis but used too much it can also CAUSE it! If using this in the bath, it would be a good idea to do so immediately before retiring to bed.

Lavender is great as an analgesic and if in doubt is the essential oil/herb to choose. Making a tea from the dried herbs helps to break down the fibres and releases some of the essential oil held within the plant matter.
It is important to remember that Lavender is one of many options open to you. Is your neck stiff due to your working conditions, an old injury or stress? Depending on your answer will dictate which essential oil is best suited to the job.
Roman chamomile is great if the muscles are inflammed and if mixed with German chamomile then a synergistic effect takes place and makes a doubly effective remedy. The combined aroma on the other hand is an aquired taste which is why I often mix it with Rose or Ylang Ylang. A good blend if you are also feeling a little blue and less than feminine.
Peppermint is another good analgesic and is particularly indicated if your neck is giving you head aches.
If your aches and pains ate more due to stress then oils like Benzoin or Bergamot are best mixed with Lavander to give a soothing, relaxing and destressing blend that works on the physical and emotional levels.
One thing to watch out for is that Lavender used in large quantities can have the opposite effect of the well know sedative properties. So many times I have had a client say that they use lavander to try and get to sleep only to find it wakes them up. On further investigation it transpires they cover their pillow in the oil which has a stimulating effect. In order to sleep 1 or at the most two drops on a tissue place inside of the pillow case is all that is needed.
If applying the essential oils to the skin always dilute it in a carrier oil such as grape seed, Sweet Almond or Apricot oil. For every 20ml of carrier oil add 4 drops of essential oil.
Finally as lovely as the raw herb/product can be, the essential oils are the most effective part of the plant and more often than not contain the active ingredient needed. My recomendation would be to buy a basic set of oils and carrier oil and make up blends to suit your needs. There are some great books to help you do that. If you want a more professional/educational book then start with The Complete Guide to Aromatherapy by Salvatore Battaglia. It's the text book of all IFA/IFPA Aromatherapist and is the one we start with.
Hope this helps if you want more advice please contact me on mia.preston@ymail.com always happy to pass on what I know.

Lavander is a really good muscle and mind relaxant and will aid sleep, dried Lavender is normally used for its aroma and also as an insect repelant. I would normally use lavender essential oil in a compress or for inhalation via a burner or vapouriser.
keep well
Paul

An excellent first aid oil. It soothes cuts, bruises and insect bites. One of the most versatile therapeutic essence. It is used for nervous system disorders such as depression, headache, hypertension, insomnia, migraine, nervous tension, stress related conditions, PMT, sciatica, Lavender is useful in treating skin conditions lavender is for the treatment of disorders such as lumbago, muscular aches and pains, rheumatism.