A new Muslimah is suffering from anxiety and insomnia. Is it permissible for her not to fast in Ramadan?
Question

My wife is a foreigner who has become Muslim, and now she is fasting her first Ramadan, but because she is not used to fasting in Ramadan, she has started to have problems sleeping. She was taking medicine for a psychological illness, but she stopped taking it two months ago. She is by nature anxious and suffers intrusive thoughts about the simplest matters. She is afraid that if she does not sleep, she will have some kind of problem, so she took anti-anxiety medicine and did not fast. I hope that you can help me by explaining whether I should be easy going with her because it is the first Ramadan for her, and that religion is easy, or what?
Praise be to Allah.Firstly:
Ruling on one who does not fast Ramadan
Fasting Ramadan is a major obligation, and it is not permissible to be take it lightly. It is not permissible to break the fast in Ramadan  unless one has a reason such as illness or travelling. Allah, may He be exalted, says (interpretation of the meaning):
{O you who have believed, decreed upon you is fasting as it was decreed upon those before you, that you may become righteous} [al-Baqarah 2:183].
Al-Bukhari (8) and Muslim (16) narrated that Ibn ‘Umar (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “Islam is built on five (pillars): testifying that there is no god worthy of worship except Allah and that Muhammad is the Messenger of Allah, establishing prayer, giving zakah, Hajj and fasting Ramadan.”
The one who does not fast has failed to observe one of the pillars of Islam and has committed a grave major sin. In fact, some of the early generations were of the view that he is a disbeliever and apostate– we seek refuge with Allah from that.
Abu Ya‘la narrated in his Musnad from Ibn ‘Abbas (may Allah be pleased with him) that the Prophet (blessings and peace of Allah be upon him) said: “The bonds of Islam and the foundations of the faith are three, on which Islam is based. Whoever fails to do one of them becomes a disbeliever thereby and may be executed [for apostasy…this would be in an Islamic state and there would be due process]: testifying that there is no god worthy of worship except Allah, offering the prescribed prayers, and fasting in Ramadan.
This hadith was classed as sahih by adh-Dhahabi; it was classed as hasan by al-Haythami in Majma‘ az-Zawaid (1/48) and al-Mundhiri in at-Targhib wa’t-Tarhib, no. 805, 1486; it was classed as da‘if (weak) by al-Albani in as-Silsilah ad-Da‘ifah, no. 94.
Adh-Dhahabi said in al-Kabair, p. 64: Among the believers it is established that whoever fails to fast the month of Ramadan, without being sick and without any excuse that would make that permissible, is worse than the zani and the one who is addicted to alcohol. In fact, they doubted whether he was a Muslim, and thought that he was a heretic. End quote.
What has been soundly narrated of warnings against failing to fast is that which was narrated by Ibn Khuzaymah (1986) and Ibn Hibban (7491) from Abu Umamah al-Bahili, who said: I heard the Messenger of Allah (blessings and peace of Allah be upon him) say:
Whilst I was sleeping, two men came to me and took hold of my upper arm, and brought me to a rugged mountain. They said: ‘Climb up.’ I said: ‘I cannot do it.’ They said: ‘We will make it easy for you.’ So I climbed up until I was at the top of the mountain. There I heard loud voices. I said: ‘What are these voices?’ They said: ‘This is the screaming of the people of Hell.’ Then I was taken and I saw people suspended by their ankles, with the corners of their mouths torn and pouring with blood. I said: ‘Who are these?’ They said: ‘These are the people who broke their fast before it was time to do so.’” Classed as sahih by al-Albani in Sahih Mawarid al-Zam‘an, 1509. 
Al-Albani (may Allah have mercy on him) commented: I say: This is the punishment of the one who fasted then deliberately broke his fast before the time for iftar had come. So how about one who does not fast at all? We ask Allah to keep us safe and sound in this world and in the Hereafter.
Secondly:
What kind of sickness makes it permissible to break the fast?
The kind of sickness that makes it permissible to break the fast  is sickness that will cause real hardship to the one who fasts.
An-Nawawi said in al-Majmu‘ (6/261):
The sick person who is unable to fast because of a sickness from which there is hope of recovery is not obliged to fast.… This applies if he will suffer real hardship when fasting. It is not stipulated that he should have reached the state in which he is unable to fast at all. Rather our companions said: For it to be permissible not to fast, it is stipulated that fasting should cause significant hardship that makes it difficult to fast. End quote.
And he said:
With regard to mild sickness that does not cause real hardship, it is not permissible for him not to fast, and there is no difference of opinion among us concerning that." (Al-Majmu‘  6/261).
If your wife who is a new Muslim will not face hardship if she fasts, then it is not permissible for her not to fast. You must explain that to her, and tell her that not fasting is a major sin. She should consult a doctor about the sleep issues and anxiety, and there is nothing wrong with taking medicine for that, if necessary. Whatever she needs of medicine to help her sleep or deal with anxiety, and the like, can be taken at night, so long as that is possible, so that she can maintain her fast and not transgress the sanctity of the month just because of anxiety or anxious thoughts.
And Allah knows best.